Optical filter

ABSTRACT

An optical filter (1a) includes a UV-IR-absorbing layer and has the following characteristics (i) to (v) when light with wavelengths of 300 nm to 1200 nm is incident at an incident angle of 0°: (i) an average transmittance of 78% or more in the wavelength range of 450 nm to 600 nm; (ii) a spectral transmittance of 1% or less in the wavelength range of 750 nm to 1080 nm; (iii) a spectral transmittance of 1% or less in the wavelength range of 300 nm to 350 nm; (iv) a decreasing spectral transmittance with increasing wavelength in the wavelength range of 600 nm to 750 nm and a first IR cut-off wavelength in the wavelength range of 620 nm to 680 nm; and (v) an increasing spectral transmittance with increasing wavelength in the wavelength range of 350 nm to 450 nm and a first UV cut-off wavelength in the wavelength range of 380 nm to 430 nm.

TECHNICAL FIELD

The present invention relates to an optical filter.

BACKGROUND ART

In imaging apparatuses employing an imaging sensor such as a chargecoupled device (CCD) or a complementary metal oxide semiconductor(CMOS), any of various optical filters is disposed ahead of the imagingsensor in order to obtain an image with good color reproduction. Imagingsensors generally have spectral sensitivity over a wide wavelength rangefrom the ultraviolet to infrared regions. The visual sensitivity ofhumans lies solely in the visible region. Thus, a technique is known inwhich an optical filter shielding against infrared light or ultravioletlight is disposed ahead of an imaging sensor in an imaging apparatus inorder to allow the spectral sensitivity of the imaging sensor toapproximate to the visual sensitivity of humans.

There are the following types of optical filters: optical filters usinglight reflection; and optical filters using light absorption. Examplesof the former include an optical filter including a dielectricmultilayer film, and examples of the latter include an optical filterincluding a film containing a light absorber capable of absorbing lightwith a given wavelength. The latter are desirable in view of theirspectral properties less likely to vary depending on the incident angleof incident light.

For example, Patent Literature 1 describes a near-infrared-absorbingfilter formed of a near-infrared absorber and resin. The near-infraredabsorber may include a particular phosphonic acid compound, particularphosphoric acid ester compound, and copper salt. The particularphosphonic acid compound has a monovalent group R¹ bonded to aphosphorus atom P and represented by —CH₂CH₂—R¹¹. R¹¹ represents ahydrogen atom, an alkyl group having 1 to 20 carbon atoms, or afluorinated alkyl group having 1 to 20 carbon atoms.

CITATION LIST

Literature 1: JP 2011-203467 A

SUMMARY OF INVENTION Technical Problem

Although the near-infrared-absorbing filter described in PatentLiterature 1 can effectively absorb light with wavelengths of 800 nm to1200 nm, it is difficult to say that the near-infrared-absorbing filterdescribed in Patent Literature 1 has desirable light absorptionproperties in the wavelength range of 350 nm to 400 nm and thewavelength range of 650 nm to 800 nm. Therefore, the present inventionprovides an optical filter capable of exhibiting, with a simpleconfiguration, desirable optical characteristics that are unachievableby only the near-infrared-absorbing filter described in PatentLiterature 1.

Solution to Problem

The present invention provides an optical filter including:

a UV-IR-absorbing layer capable of absorbing infrared light andultraviolet light, wherein

when light with wavelengths of 300 nm to 1200 nm is incident at anincident angle of 0°,

(i) the optical filter has an average transmittance of 78% or more inthe wavelength range of 450 nm to 600 nm,

(ii) the optical filter has a spectral transmittance of 1% or less inthe wavelength range of 750 nm to 1080 nm,

(iii) the optical filter has a spectral transmittance of 1% or less inthe wavelength range of 300 nm to 350 nm,

(iv) the optical filter has a decreasing spectral transmittance withincreasing wavelength in the wavelength range of 600 nm to 750 nm and afirst IR cut-off wavelength which lies in the wavelength range of 600 nmto 750 nm and at which the spectral transmittance is 50% is in thewavelength range of 620 nm to 680 nm, and

(v) the optical filter has an increasing spectral transmittance withincreasing wavelength in the wavelength range of 350 nm to 450 nm and afirst UV cut-off wavelength which lies in the wavelength range of 350 nmto 450 nm and at which the spectral transmittance is 50% is in thewavelength range of 380 nm to 430 nm.

Advantageous Effects of Invention

The above optical filter can exhibit the desirable opticalcharacteristics with a simple configuration.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a cross-sectional view showing an example of an opticalfilter of the present invention.

FIG. 1B is a cross-sectional view showing another example of the opticalfilter of the present invention.

FIG. 1C is a cross-sectional view showing yet another example of theoptical filter of the present invention.

FIG. 1D is a cross-sectional view showing yet another example of theoptical filter of the present invention.

FIG. 1E is a cross-sectional view showing yet another example of theoptical filter of the present invention.

FIG. 1F is a cross-sectional view showing yet another example of theoptical filter of the present invention.

FIG. 2 is a cross-sectional view showing an example of a camera moduleincluding the optical filter of the present invention.

FIG. 3 shows transmittance spectra of an optical filter according toExample 1.

FIG. 4 shows transmittance spectra of an optical filter according toExample 2.

FIG. 5 shows transmittance spectra of an optical filter according toExample 16.

FIG. 6 shows transmittance spectra of an optical filter according toExample 17.

FIG. 7 shows transmittance spectra of an optical filter according toExample 18.

FIG. 8A shows a transmittance spectrum of an infrared-absorbing glasssubstrate used in Example 21.

FIG. 8B shows a transmittance spectrum of an optical filter according toExample 21.

FIG. 9 shows a transmittance spectrum of an optical filter according toExample 22.

FIG. 10 shows a transmittance spectrum of an optical filter according toExample 23.

FIG. 11 shows a transmittance spectrum of an optical filter according toExample 24.

FIG. 12 shows a transmittance spectrum of an optical filter according toExample 38.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings. The following description is directed to someexamples of the present invention, and the present invention is notlimited by these examples.

In some cases, it is desirable for optical filters to have properties ofpermitting transmission of light with wavelengths of 450 nm to 600 nmand cutting off light with wavelengths of 300 nm to 400 nm andwavelengths of 650 nm to 1100 nm. However, for example, the opticalfilter described in Patent Literature 1 does not have sufficient lightabsorption properties in the wavelength range of 350 nm to 400 nm andthe wavelength range of 650 nm to 800 nm, and a light-absorbing layer orlight-reflecting film is additionally needed to cut off light withwavelengths of 350 nm to 400 nm and wavelengths of 650 nm to 800 nm. Asjust described above, it is difficult to achieve an optical filterhaving the above desirable properties with a simple structure (forexample, a single layer). In fact, the present inventor went throughmuch trial and error to achieve an optical filter having the abovedesirable properties with a simple structure. That eventually led thepresent inventor to the optical filter according to the presentinvention.

As shown in FIG. 1A, the optical filter 1 a includes a UV-IR-absorbinglayer 10. The UV-IR-absorbing layer 10 is a layer capable of absorbinginfrared light and ultraviolet light. When light with wavelengths of 300nm to 1200 nm is incident at an incident angle of 0°, the optical filter1 a exhibits the following optical characteristics (i) to (v).

-   (i) An average transmittance of 78% or more in the wavelength range    of 450 nm to 600 nm-   (ii) A spectral transmittance of 1% or less in the wavelength range    of 750 nm to 1080 nm-   (iii) A spectral transmittance of 1% or less in the wavelength range    of 300 nm to 350 nm-   (iv) A decreasing spectral transmittance with increasing wavelength    in the wavelength range of 600 nm to 750 nm and a first IR cut-off    wavelength in the wavelength range of 620 nm to 680 nm-   (v) An increasing spectral transmittance with increasing wavelength    in the wavelength range of 350 nm to 450 nm and a first UV cut-off    wavelength in the wavelength range of 380 nm to 430 nm

Herein, the term “spectral transmittance” refers to a transmittanceobtained when light with a given wavelength is incident on an objectsuch as a specimen, the term “average transmittance” refers to anaverage of spectral transmittances in a given wavelength range, and theterm “maximum transmittance” refers to the maximum spectraltransmittance in a given wavelength range. Additionally, the term“transmittance spectrum” herein refers to one in which spectraltransmittances at wavelengths in a given wavelength range are arrangedin the wavelength order.

Herein, the term “IR cut-off wavelength” refers to a wavelength at whichthe spectral transmittance is 50% when light with wavelengths of 300 nmto 1200 nm is incident on an optical filter at a given incident angleand which lies in the wavelength range of 600 nm or more. The term“first IR cut-off wavelength” refers to an IR cut-off wavelength forlight incident on an optical filter at an incident angle of 0°.Additionally, the term “UV cut-off wavelength” refers to a wavelength atwhich the spectral transmittance is 50% when light with wavelengths of300 nm to 1200 nm is incident on an optical filter at a given incidentangle and which lies in the wavelength range of 450 nm or less. The term“first UV cut-off wavelength” is a UV cut-off wavelength for lightincident on an optical filter at an incident angle of 0°.

As the optical filter 1 a exhibits the above optical characteristics (i)to (v), the optical filter 1 a permits transmission of a large amount oflight with wavelengths of 450 nm to 600 nm and can effectively cut offlight with wavelengths of 300 nm to 400 nm and wavelengths of 650 nm to1100 nm. Therefore, a transmittance spectrum of the optical filter 1 aconforms better to the visual sensitivity of humans than does atransmittance spectrum of the near-infrared-absorbing filter describedin Patent Literature 1. Moreover, the optical filter 1 a can exhibit theabove optical characteristics (i) to (v) without a layer other than theUV-IR-absorbing layer 10.

As to the above (i), the optical filter 1 a desirably has an averagetransmittance of 80% or more and more desirably an average transmittanceof 82% or more in the wavelength range of 450 nm to 600 nm.

As to the above (iii), the optical filter 1 a desirably has a spectraltransmittance of 1% or less in the wavelength range of 300 nm to 360 nm.This allows the optical filter 1 a to more effectively cut off light inthe ultraviolet region.

As to the above (iv), the first IR cut-off wavelength (a wavelength atwhich the spectral transmittance is 50%) desirably lies in thewavelength range of 630 nm to 650 nm. In this case, a transmittancespectrum of the optical filter 1 a conforms better to the visualsensitivity of humans.

As to the above (v), the first UV cut-off wavelength (a wavelength atwhich the spectral transmittance is 50%) desirably lies in thewavelength range of 390 nm to 420 nm. In this case, a transmittancespectrum of the optical filter 1 a conforms better to the visualsensitivity of humans.

The optical filter 1 a desirably exhibits the following opticalcharacteristic (vi) when light with wavelengths of 300 nm to 1200 nm isincident at an incident angle of 0°. The optical filter 1 a can thusshield against infrared light with a relatively long wavelength (awavelength of 1000 to 1100 nm). Conventionally, a light-reflecting filmformed of a dielectric multilayer film is commonly used to cut off lightwith such a wavelength. The optical filter 1 a can effectively cut offlight with such a wavelength without using such a dielectric multilayerfilm. Even when a light-reflecting film formed of a dielectricmultilayer film is necessary, the optical filter 1 a can lower areflection performance level required of the light-reflecting film.Therefore, the number of dielectrics laminated in the light-reflectingfilm can be decreased and the cost needed to form the light-reflectingfilm can be decreased.

-   (vi) A spectral transmittance of 3% or less in the wavelength range    of 1000 to 1100 nm

The optical filter 1 a desirably exhibits the following opticalcharacteristic (vii) when light with wavelengths of 300 nm to 1200 nm isincident at an incident angle of 0°. In this case, infrared light with alonger wavelength (1100 to 1200 nm) can be cut off. This allows theoptical filter 1 a to effectively cut off light with such a wavelengthwithout using a dielectric multilayer film or with a small number ofdielectrics laminated in a dielectric multilayer film.

-   (vii) A spectral transmittance of 15% or less in the wavelength    range of 1100 to 1200 nm

For example, in the optical filter 1 a, an absolute value of adifference between a second IR cut-off wavelength and the first IRcut-off wavelength is 10 nm or less (optical characteristic (viii)). Thesecond IR cut-off wavelength is an IR cut-off wavelength obtained whenlight with wavelengths of 300 nm to 1200 nm is incident on the opticalfilter 1 a at an incident angle of 40°. In this case, the transmittanceproperties of the optical filter 1 a in the vicinity of the first IRcut-off wavelength are less likely to vary with the incident angle oflight incident on the optical filter 1 a. Consequently, a centralportion and peripheral portion of an image obtained using an imagingapparatus in which the optical filter 1 a is disposed ahead of animaging sensor can be prevented from presenting unintended color tones.

In the optical filter 1 a, the absolute value of the difference betweenthe second IR cut-off wavelength and first IR cut-off wavelength isdesirably 5 nm or less.

For example, in the optical filter 1 a, an absolute value of adifference between a third IR cut-off wavelength and the first IRcut-off wavelength is 15 nm or less (optical characteristic (ix)). Thethird IR cut-off wavelength is an IR cut-off wavelength obtained whenlight with wavelengths of 300 nm to 1200 nm is incident on the opticalfilter 1 a at an incident angle of 50°. In this case, even when theincident angle of light incident on the optical filter 1 a greatlychanges, variation in transmittance properties in the vicinity of thefirst IR cut-off wavelength of the optical filter 1 a can be reduced.Consequently, high-quality images can be easily obtained when theoptical filter 1 a is disposed ahead of an imaging sensor in an imagingapparatus capable of capturing images at a wide angle of view.

For example, in the optical filter 1 a, an absolute value of adifference between a fourth IR cut-off wavelength and the first IRcut-off wavelength is 20 nm or less. The fourth IR cut-off wavelength isan IR cut-off wavelength obtained when light with wavelengths of 300 nmto 1200 nm is incident on the optical filter 1 a at an incident angle of60°. In this case, high-quality images can be easily obtained when theoptical filter 1 a is disposed ahead of an imaging sensor in an imagingapparatus capable of capturing images at a wide angle of view.

For example, in the optical filter 1 a, an absolute value of adifference between a second UV cut-off wavelength and the first UVcut-off wavelength is 10 nm or less (optical characteristic (x)). Thesecond UV cut-off wavelength is a UV cut-off wavelength obtained whenlight with wavelengths of 300 nm to 1200 nm is incident on the opticalfilter 1 a at an incident angle of 40°. In this case, the transmittanceproperties of the optical filter 1 a in the vicinity of the first UVcut-off wavelength are less likely to vary with the incident angle oflight incident on the optical filter 1 a. Consequently, a centralportion and peripheral portion of an image obtained using an imagingapparatus in which the optical filter 1 a is disposed ahead of animaging sensor can be prevented from presenting unintended color tones.

In the optical filter 1 a, the absolute value of the difference betweenthe second UV cut-off wavelength and first UV cut-off wavelength isdesirably 5 nm or less.

For example, in the optical filter 1 a, an absolute value of adifference between a third UV cut-off wavelength and the first UVcut-off wavelength is 15 nm or less (optical characteristic (xi)). Thethird UV cut-off wavelength is a UV cut-off wavelength obtained whenlight with wavelengths of 300 nm to 1200 nm is incident on the opticalfilter 1 a at an incident angle of 50°. In this case, even when theincident angle of light incident on the optical filter 1 a greatlychanges, variation in transmittance properties in the vicinity of thefirst UV cut-off wavelength of the optical filter 1 a can be reduced.Consequently, high-quality images can be easily obtained when theoptical filter 1 a is disposed ahead of an imaging sensor in an imagingapparatus capable of capturing images at a wide angle of view.

For example, in the optical filter 1 a, an absolute value of adifference between a fourth UV cut-off wavelength and the first UVcut-off wavelength is 20 nm or less. The fourth UV cut-off wavelength isa UV cut-off wavelength obtained when light with wavelengths of 300 nmto 1200 nm is incident on the optical filter 1 a at an incident angle of60°. In this case, high-quality images can be easily obtained when theoptical filter 1 a is disposed ahead of an imaging sensor in an imagingapparatus capable of capturing images at a wide angle of view.

The optical filter 1 a desirably exhibits the following opticalcharacteristic (xii) when light with wavelengths of 300 nm to 1200 nm isincident at an incident angle of 0°.

-   (xii) A spectral transmittance of 0.5% or less and more desirably a    spectral transmittance of 0.1% or less in the wavelength range of    800 to 950 nm

The optical filter 1 a desirably further exhibits the following opticalcharacteristic (xiii) when light with wavelengths of 300 nm to 1200 nmis incident at an incident angle of 0°.

-   (xiii) A spectral transmittance of 0.5% or less and more desirably a    spectral transmittance of 0.1% or less in the wavelength range of    800 to 1000 nm

RGB color filters used in imaging apparatuses not only permittransmission of light in wavelength ranges of the corresponding RGBcolors but sometimes permit transmission of light with wavelengths of800 nm or more. Therefore, in the case where an infrared cut filter usedin an imaging apparatus has a spectral transmittance not reduced to acertain level in the above wavelength range, light in the abovewavelength range is incident on a pixel of an imaging sensor and thecorresponding signal is output from the pixel. When the imagingapparatus is used to obtain a digital image under a sufficiently largeamount of visible light, the obtained digital image is not greatlyaffected by a small amount of infrared light transmitted through a colorfilter and received by a pixel of the imaging sensor. However, suchinfrared light tends to have a stronger influence under a small amountof visible light or on a dark part of an image, and sometimes a bluishor reddish color is added to the image.

As described above, color filters used along with imaging sensors suchas a CMOS and CCD sometimes permit transmission of light in thewavelength range of 800 to 950 nm or 800 to 1000 nm. The optical filter1 a having the above optical characteristics (xii) and (xiii) canprevent the above defect of images.

The UV-IR-absorbing layer 10 is not particularly limited as long as theUV-IR-absorbing layer 10 absorbs infrared light and ultraviolet light toallow the optical filter 1 a to exhibit the above opticalcharacteristics (i) to (v). The UV-IR-absorbing layer 10, for example,includes a UV-IR absorber formed by a phosphonic acid and copper ion.

When the UV-IR-absorbing layer 10 includes the UV-IR absorber formed bya phosphonic acid and copper ion, the phosphonic acid includes, forexample, a first phosphonic acid having an aryl group. In the firstphosphonic acid, the aryl group is bonded to a phosphorus atom. Thus,the optical filter 1 a easily exhibits the above optical characteristics(i) to (v).

The aryl group of the first phosphonic acid is, for example, a phenylgroup, benzyl group, toluyl group, nitrophenyl group, hydroxyphenylgroup, halogenated phenyl group in which at least one hydrogen atom of aphenyl group is substituted by a halogen atom, or halogenated benzylgroup in which at least one hydrogen atom of a benzene ring of a benzylgroup is substituted by a halogen atom. The first phosphonic aciddesirably includes a portion that has the halogenated phenyl group. Inthat case, the optical filter 1 a easily exhibits the above opticalcharacteristics (i) to (v) more reliably.

When the UV-IR-absorbing layer 10 includes the UV-IR absorber formed bythe phosphonic acid and copper ion, the phosphonic acid desirablyfurther includes a second phosphonic acid having an alkyl group. In thesecond phosphonic acid, the alkyl group is bonded to a phosphorus atom.

The alkyl group of the second phosphonic acid is, for example, an alkylgroup having 6 or less carbon atoms. This alkyl group may be linear orbranched.

When the UV-IR-absorbing layer 10 includes the UV-IR absorber formed bythe phosphonic acid and copper ion, the UV-IR-absorbing layer 10desirably further includes a phosphoric acid ester allowing the UV-IRabsorber to be dispersed and matrix resin.

The phosphoric acid ester included in the UV-IR-absorbing layer 10 isnot limited to any particular one, as long as the phosphoric acid esterallows good dispersion of the UV-IR absorber. For example, thephosphoric acid ester includes at least one of a phosphoric acid diesterrepresented by the following formula (c1) and a phosphoric acidmonoester represented by the following formula (c2). In the formulae(c1) and (c2), R₂₁, R₂₂, and R₃ are each a monovalent functional grouprepresented by —(CH₂CH₂O)_(n)R₄, wherein n is an integer of 1 to 25 andR₄ is an alkyl group having 6 to 25 carbon atoms. R₂₁, R₂₂, and R₃ maybe the same or different functional groups.

The phosphoric acid ester is not particularly limited. The phosphoricacid ester can be, for example, PLYSURF A208N (polyoxyethylene alkyl(C12, C13) ether phosphoric acid ester), PLYSURF A208F (polyoxyethylenealkyl (C8) ether phosphoric acid ester), PLYSURF A208B (polyoxyethylenelauryl ether phosphoric acid ester), PLYSURF A219B (polyoxyethylenelauryl ether phosphoric acid ester), PLYSURF AL (polyoxyethylenestyrenated phenylether phosphoric acid ester), PLYSURF A212C(polyoxyethylene tridecyl ether phosphoric acid ester), or PLYSURF A215C(polyoxyethylene tridecyl ether phosphoric acid ester). All of these areproducts manufactured by DKS Co., Ltd. The phosphoric acid ester can beNIKKOL DDP-2 (polyoxyethylene alkyl ether phosphoric acid ester), NIKKOLDDP-4 (polyoxyethylene alkyl ether phosphoric acid ester), or NIKKOLDDP-6 (polyoxyethylene alkyl ether phosphoric acid ester). All of theseare products manufactured by Nikko Chemicals Co., Ltd.

The matrix resin included in the UV-IR-absorbing layer 10 is, forexample, a heat-curable or ultraviolet-curable resin in which the UV-IRabsorber is dispersible. Additionally, as the matrix resin can be used aresin that has a transmittance of, for example, 70% or more, desirably75% or more, and more desirably 80% or more for light with wavelengthsof 350 nm to 900 nm in the form of a 0.1-mm-thick resin layer. Thecontent of the phosphonic acid is, for example, 3 to 180 parts by masswith respect to 100 parts by mass of the matrix resin.

The matrix resin included in the UV-IR-absorbing layer 10 is notparticularly limited as long as the above properties are satisfied. Thematrix resin is, for example, a (poly)olefin resin, polyimide resin,polyvinyl butyral resin, polycarbonate resin, polyamide resin,polysulfone resin, polyethersulfone resin, polyamideimide resin,(modified) acrylic resin, epoxy resin, or silicone resin. The matrixresin may contain an aryl group such as a phenyl group and is desirablya silicone resin containing an aryl group such as a phenyl group. If theUV-IR-absorbing layer 10 is excessively hard (rigid), the likelihood ofcure shrinkage-induced cracking during the production process of theoptical filter 1 a increases with increasing thickness of theUV-IR-absorbing layer 10. When the matrix resin is a silicone resincontaining an aryl group, the UV-IR-absorbing layer 10 is likely to havehigh crack resistance. Moreover, with the use of a silicone resincontaining an aryl group, the UV-IR absorber formed by the abovephosphonic acid and copper ion is less likely to be aggregated whenincluded. Further, when the matrix resin of the UV-IR-absorbing layer 10is a silicone resin containing an aryl group, it is desirable for thephosphoric acid ester included in the UV-IR-absorbing layer 10 to have aflexible, linear organic functional group, such as an oxyalkyl group,just as does the phosphoric acid ester represented by the formula (c1)or formula (c2). This is because interaction derived from thecombination of the above phosphonic acid, a silicone resin containing anaryl group, and phosphoric acid ester having a linear organic functionalgroup such as an oxyalkyl group makes aggregation of the UV-IR absorberless likely and can impart good rigidity and good flexibility to theUV-IR-absorbing layer. Specific examples of the silicone resin availableas the matrix resin include KR-255, KR-300, KR-2621-1, KR-211, KR-311,KR-216, KR-212, and KR-251. All of these are silicone resinsmanufactured by Shin-Etsu Chemical Co., Ltd.

As shown in FIG. 1A, the optical filter 1 a further includes, forexample, a transparent dielectric substrate 20, and at least portion ofone principal surface of the transparent dielectric substrate 20 iscovered with the UV-IR-absorbing layer 10. The transparent dielectricsubstrate 20 is not limited to any particular one as long as thetransparent dielectric substrate 20 is a dielectric substrate having ahigh average transmittance (e.g., 80% or more) in the wavelength rangeof 450 nm to 600 nm. In some cases, the transparent dielectric substrate20 may have the ability to absorb light in the ultraviolet region orinfrared region.

The transparent dielectric substrate 20 is, for example, made of glassor resin. When the transparent dielectric substrate 20 is made of glass,the glass is, for example, borosilicate glass such as D 263, soda-limeglass (blue plate glass), white sheet glass such as B 270, alkali-freeglass, or infrared-absorbing glass such as copper-containing phosphateglass or copper-containing fluorophosphate glass. When the transparentdielectric substrate 20 is made of infrared-absorbing glass such ascopper-containing phosphate glass or copper-containing fluorophosphateglass, the infrared absorption performance necessary for the opticalfilter 1 a can be achieved by a combination of the infrared absorptionperformance of the transparent dielectric substrate 20 and the infraredabsorption performance of the UV-IR-absorbing layer 10. Therefore, thelevel of the infrared absorption performance required of theUV-IR-absorbing layer 10 can be lowered. Examples of such aninfrared-absorbing glass include BG-60, BG-61, BG-62, BG-63, and BG-67manufactured by SCHOTT AG, 500EXL manufactured by Nippon Electric GlassCo., Ltd., and CM5000, CM500, C5000, and C500S manufactured by HOYACORPORATION. Moreover, the infrared-absorbing glass may have ultravioletabsorption properties.

The transparent dielectric substrate 20 may be a transparent crystallinesubstrate, such as magnesium oxide, sapphire, or quartz. For example,sapphire is very hard and is thus scratch resistant. Therefore, as ascratch-resistant protective material (protective filter), asheet-shaped sapphire is sometimes disposed ahead of a camera module orlens included in mobile devices such as smartphones and mobile phones.Formation of the UV-IR-absorbing layer 10 on such a sheet-shapedsapphire makes it possible to protect camera modules and lenses andshield against ultraviolet light or infrared light. This eliminates theneed to dispose an optical filter having ultraviolet- orinfrared-shielding performance around an imaging sensor such as a CCD orCMOS or inside a camera module. Therefore, the formation of theUV-IR-absorbing layer 10 on a sheet-shaped sapphire can contribute toachievement of camera modules reduced in profile.

When the transparent dielectric substrate 20 is made of resin, the resinis, for example, a (poly)olefin resin, polyimide resin, polyvinylbutyral resin, polycarbonate resin, polyamide resin, polysulfone resin,polyethersulfone resin, polyamideimide resin, (modified) acrylic resin,epoxy resin, or silicone resin.

As shown in FIG. 1A, the UV-IR-absorbing layer 10 is, for example,formed as a single layer in the optical filter 1 a. In this case, theoptical filter 1 a has a simple structure.

The optical filter 1 a can be produced, for example, by applying acomposition (UV-IR-absorbing composition) for forming theUV-IR-absorbing layer 10 to one principal surface of the transparentdielectric substrate 20 to form a film and drying the film. The methodfor preparing the UV-IR-absorbing composition and the method forproducing the optical filter 1 a will be described with an example inwhich the UV-IR-absorbing layer 10 includes the UV-IR absorber formed bythe phosphonic acid and copper ion.

First, an exemplary method for preparing the UV-IR-absorbing compositionwill now be described. A copper salt such as copper acetate monohydrateis added to a given solvent such as tetrahydrofuran (THF), and themixture is stirred to give a copper salt solution. To this copper saltsolution is then added a phosphoric acid ester compound such as aphosphoric acid diester represented by the formula (c1) or a phosphoricacid monoester represented by the formula (c2), and the mixture isstirred to prepare a solution A. A solution B is also prepared by addingthe first phosphonic acid to a given solvent such as THF and stirringthe mixture. When a plurality of phosphonic acids are used as the firstphosphonic acid, the solution B may be prepared by adding eachphosphonic acid to a given solvent such as THF, stirring the mixture,and mixing a plurality of preliminary liquids each prepared to contain adifferent phosphonic acid. In the preparation of the solution B, analkoxysilane monomer is desirably added.

The addition of an alkoxysilane monomer to the UV-IR-absorbingcomposition can prevent particles of the UV-IR absorber from aggregatingwith each other. This enables the UV-IR absorber to be dispersed well inthe UV-IR-absorbing composition even when the content of the phosphoricacid ester is decreased. When the UV-IR-absorbing composition is used toproduce the optical filter 1 a, a treatment is performed so thatsufficient hydrolysis and polycondensation reactions of the alkoxysilanemonomer occur. Owing to the treatment, a siloxane bond (—Si—O—Si—) isformed and the optical filter 1 a has good moisture resistance. Theoptical filter 1 a additionally has good heat resistance. This isbecause a siloxane bond is greater in binding energy and chemically morestable than bonds such as a —C—C— bond and —C—O— bond and is thusexcellent in heat resistance and moisture resistance.

Next, the solution B is added to the solution A while the solution A isstirred, and the mixture is further stirred for a given period of time.To the resultant solution is then added a given solvent such as toluene,and the mixture is stirred to obtain a solution C. Subsequently, thesolution C is subjected to solvent removal under heating for a givenperiod of time to obtain a solution D. This process removes the solventsuch as THF and the component such as acetic acid (boiling point: about118° C.) generated by disassociation of the copper salt and yields aUV-IR absorber formed by the first phosphonic acid and copper ion. Thetemperature at which the solution C is heated is chosen based on theboiling point of the to-be-removed component disassociated from thecopper salt. During the solvent removal, the solvent such as toluene(boiling point: about 110° C.) used to obtain the solution C is alsoevaporated. A certain amount of this solvent desirably remains in theUV-IR-absorbing composition. This is preferably taken into account indetermining the amount of the solvent to be added and the time period ofthe solvent removal. To obtain the solution C, o-xylene (boiling point:about 144° C.) may be used instead of toluene. In this case, the amountof o-xylene to be added can be reduced to about one-fourth of the amountof toluene to be added, because the boiling point of o-xylene is higherthan the boiling point of toluene.

When the UV-IR-absorbing composition further includes the secondphosphonic acid, a solution H is additionally prepared for example, asfollows. First, a copper salt such as copper acetate monohydrate isadded to a given solvent such as tetrahydrofuran (THF), and the mixtureis stirred to give a copper salt solution. To this copper salt solutionis then added a phosphoric acid ester compound such as a phosphoric aciddiester represented by the formula (c1) or a phosphoric acid monoesterrepresented by the formula (c2), and the mixture is stirred to prepare asolution E. A solution F is also prepared by adding the secondphosphonic acid to a given solvent such as THF and stirring the mixture.When a plurality of phosphonic acids are used as the second phosphonicacid, the solution F may be prepared by adding each phosphonic acid to agiven solvent such as THF, stirring the mixture, and mixing a pluralityof preliminary liquids each prepared to contain a different phosphonicacid. The solution F is added to the solution E while the solution E isstirred, and the mixture is further stirred for a given period of time.To the resultant solution is then added a given solvent such as toluene,and the mixture is stirred to obtain a solution G. Subsequently, thesolution G is subjected to solvent removal under heating for a givenperiod of time to obtain a solution H. This process removes the solventsuch as THF and the component such as acetic acid generated bydisassociation of the copper salt and yields another UV-IR absorberformed by the second phosphonic acid and copper ion. The temperature atwhich the solution G is heated is determined as in the case of thesolution C. The solvent for obtaining the solution G is also determinedas in the case of the solution C.

The UV-IR-absorbing composition can be prepared by adding the matrixresin such as a silicone resin to the solution D and stirring themixture. When the UV-IR-absorbing composition includes the UV-IRabsorber formed by the second phosphonic acid and copper ion, theUV-IR-absorbing composition can be prepared by adding the matrix resinsuch as a silicone resin to the solution D, stirring the mixture toobtain a solution I, and further adding the solution H to the solution Iand stirring the mixture.

The UV-IR-absorbing composition is applied to one principal surface ofthe transparent dielectric substrate 20 to form a film. For example, theUV-IR-absorbing composition in a liquid form is applied by spin coatingor with a dispenser to one principal surface of the transparentdielectric substrate 20 to form a film. Next, this film is subjected toa given heat treatment to cure the film. For example, the film isexposed to an environment at a temperature of 50° C. to 200° C. The filmis subjected to a humidification treatment, if necessary, tosufficiently hydrolyze the alkoxysilane monomer included in theUV-IR-absorbing composition. For example, the cured film is exposed toan environment at a temperature of 40° C. to 100° C. and a relativehumidity of 40% to 100%. A repeating structure (Si—O)_(n) of a siloxanebond is thus formed. The optical filter 1 a can be produced in thismanner. In common hydrolysis and polycondensation reactions of analkoxysilane containing a monomer, both the alkoxysilane and water arein a liquid composition sometimes. However, if water is added beforehandto the UV-IR-absorbing composition to produce the optical filter, thephosphoric acid ester or UV-IR absorber is deteriorated in the course ofthe formation of the UV-IR-absorbing layer, and the UV-IR absorptionperformance can be decreased or the durability of the optical filter canbe impaired. Therefore, the humidification treatment is desirablyperformed after the film is cured by the given heat treatment.

When the transparent dielectric substrate 20 is a glass substrate, aresin layer including a silane coupling agent may be formed between thetransparent dielectric substrate 20 and UV-IR-absorbing layer 10 toimprove the adhesion between the transparent dielectric substrate 20 andUV-IR-absorbing layer 10.

<Modifications>

The optical filter 1 a can be modified in various respects. For example,the optical filter 1 a may be modified to optical filters 1 b to 1 fshown in FIG. 1B to FIG. 1F. The optical filters 1 b to 1 f areconfigured in the same manner as the optical filter 1 a, unlessotherwise described. The components of the optical filters 1 b to 1 fthat are the same as or correspond to those of the optical filter 1 aare denoted by the same reference characters, and detailed descriptionsof such components are omitted. The description given for the opticalfilter 1 a can apply to the optical filters 1 b to 1 f, unless there istechnical inconsistency.

As shown in FIG. 1B, the optical filter 1 b according to another exampleof the present invention has the UV-IR-absorbing layers 10 formed onboth principal surfaces of the transparent dielectric substrate 20.Therefore, the optical filter 1 b can exhibit the opticalcharacteristics (i) to (v) owing to the two UV-IR-absorbing layers 10rather than one UV-IR-absorbing layer 10. The UV-IR-absorbing layers 10on both principal surfaces of the transparent dielectric substrate 20may have the same or different thicknesses. That is, the formation ofthe UV-IR-absorbing layers 10 on both principal surfaces of thetransparent dielectric substrate 20 is done so that the twoUV-IR-absorbing layers 10 account for equal or unequal proportions ofthe UV-IR-absorbing layer thickness required for the optical filter 1 bto have desired optical properties. Thus, the thicknesses of theUV-IR-absorbing layers 10 formed on both principal surfaces of thetransparent dielectric substrate 20 are relatively small. Thus, theinternal pressure of the film is low and occurrence of a crack can beprevented. Additionally, it is possible to shorten the time spent on theapplication of the UV-IR-absorbing composition in a liquid form andshorten the time taken for the curing of the film of the UV-IR-absorbingcomposition applied. If the UV-IR-absorbing layer 10 is formed only onone principal surface of the transparent dielectric substrate 20 that isthin, the optical filter may be warped due to a stress induced byshrinkage occurring during formation of the UV-IR-absorbing layer 10from the UV-IR-absorbing composition. The formation of theUV-IR-absorbing layers 10 on both principal surfaces of the transparentdielectric substrate 20 can reduce warping of the optical filter 1 beven when the transparent dielectric substrate 20 is thin. In this caseas well, a resin layer including a silane coupling agent may be formedbetween the transparent dielectric substrate 20 and UV-IR-absorbinglayer 10 to improve the adhesion between the transparent dielectricsubstrate 20 and UV-IR-absorbing layer 10.

As shown in FIG. 1C, the optical filter 1 c according to another exampleof the present invention includes an anti-reflection film 30. Theanti-reflection film 30 is a film formed as an interface between theoptical filter 1 c and air and reducing reflection of visible light. Theanti-reflection film 30 is, for example, a film formed of a dielectricmade of, for example, a resin, an oxide, or a fluoride. Theanti-reflection film 30 may be a multilayer film formed by laminatingtwo or more types of dielectrics having different refractive indices. Inparticular, the anti-reflection film 30 may be a dielectric multilayerfilm made of a low-refractive-index material such as SiO₂ and ahigh-refractive-index material such as TiO₂ or Ta₂O₅. In this case,Fresnel reflection at the interface between the optical filter 1 c andair is reduced and the amount of visible light passing through theoptical filter 1 c can be increased. In this case as well, a resin layerincluding a silane coupling agent may be formed between the transparentdielectric substrate 20 and UV-IR-absorbing layer 10 to improve theadhesion between the transparent dielectric substrate 20 andUV-IR-absorbing layer 10. In some cases, a resin layer including asilane coupling agent may be formed between the UV-IR-absorbing layer 10and anti-reflection film 30 to improve the adhesion to theanti-reflection film 30. The anti-reflection film 30 may be disposed oneach principal surface of the optical filter 1 c, or may be disposed onone principal surface thereof.

As shown in FIG. 1D, the optical filter 1 d according to another exampleof the present invention consists only of the UV-IR-absorbing layer 10.The optical filter 1 d can be produced, for example, by applying theUV-IR-absorbing composition onto a given substrate such as a glasssubstrate, resin substrate, or metal substrate (such as a steelsubstrate or stainless steel substrate) to form a film, curing the film,and then separating the film from the substrate. The optical filter 1 dmay be produced by a melt molding method. Not including the transparentdielectric substrate 20, the optical filter 1 d is thin. The opticalfilter 1 d can thus contribute to achievement of imaging sensors andoptical systems reduced in profile.

As shown in FIG. 1E, the optical filter 1 e according to another exampleof the present invention includes the UV-IR-absorbing layer 10 and apair of the anti-reflection films 30 disposed on both sides of theUV-IR-absorbing layer 10. In this case, the optical filter 1 e cancontribute to achievement of imaging sensors and optical systems reducedin profile, and can increase the amount of visible light passingtherethrough more than the optical filter 1 d can.

As shown in FIG. 1F, the optical filter 1 f according to another exampleof the present invention includes the UV-IR-absorbing layer 10 and areflecting film 40 disposed on one principal surface of theUV-IR-absorbing layer 10 and capable of reflecting infrared light and/orultraviolet light. The reflecting film 40 is, for example, a film formedby vapor deposition of a metal such as aluminum or a dielectricmultilayer film in which a layer formed of a high-refractive-indexmaterial and a layer formed of a low-refractive-index material arealternately laminated. A material, such as TiO₂, ZrO₂, Ta₂O₅, Nb₂O₅,ZnO, or In₂O₃, having a refractive index of 1.7 to 2.5 is used as thehigh-refractive-index material. A material, such as SiO₂, Al₂O₃, orMgF₂, having a refractive index of 1.2 to 1.6 is used as thelow-refractive-index material. Examples of the method for forming thedielectric multilayer film include chemical vapor deposition (CVD),sputtering, and vacuum deposition. The reflecting film may be formed aseach principal surface of the optical filter (not shown). The reflectingfilms formed on both principal surfaces of the optical filter balancethe stress on the front side and that on the back side, and that offersan advantage of decreasing the likelihood of warping of the opticalfilter.

The optical filters 1 a to 1 f may be modified to include aninfrared-absorbing film (not shown) in addition to the UV-IR-absorbinglayer 10, if necessary. The infrared-absorbing film includes, forexample, an organic infrared absorber, such as a cyanine-based,phthalocyanine-based, squarylium-based, diimmonium-based, or azo-basedinfrared absorber or an infrared absorber composed of a metal complex.The infrared-absorbing film includes, for example, one infrared absorberor two or more infrared absorbers selected from these infraredabsorbers. The organic infrared absorber can absorb light in arelatively narrow wavelength range (absorption band) and is suitable forabsorbing light with a wavelength in a given range.

The optical filters 1 a to 1 f may be modified to include anultraviolet-absorbing film (not shown) in addition to theUV-IR-absorbing layer 10, if necessary. The ultraviolet-absorbing filmincludes, for example, an ultraviolet absorber, such as abenzophenone-based, triazine-based, indole-based, merocyanine-based, oroxazole-based ultraviolet absorber. The ultraviolet-absorbing film, forexample, includes one ultraviolet absorber or two or more ultravioletabsorbers selected from these ultraviolet absorbers. The ultravioletabsorber can include ultraviolet absorbers absorbing ultraviolet lightwith a wavelength, for example, around 300 nm to 340 nm, emitting light(fluorescence) with a wavelength longer than the absorbed wavelength,and functioning as a fluorescent agent or fluorescent brightener. Theultraviolet-absorbing film can reduce incidence of ultraviolet lightwhich deteriorates the materials, such as resin, used in the opticalfilter.

The above infrared absorber or ultraviolet absorber may be containedbeforehand in the transparent dielectric substrate 20 made of the resin.The infrared-absorbing film and ultraviolet-absorbing film each can beformed, for example, by forming a resin containing the infrared absorberor ultraviolet absorber into a film. In this case, it is necessary forthe resin to allow the infrared absorber or ultraviolet absorber to beappropriately dissolved or dispersed therein and be transparent.Examples of such a resin include a (poly)olefin resin, polyimide resin,polyvinyl butyral resin, polycarbonate resin, polyamide resin,polysulfone resin, polyethersulfone resin, polyamideimide resin,(modified) acrylic resin, epoxy resin, and silicone resin.

The optical filters 1 a to 1 f may be modified to further include areflecting film reflecting infrared light and/or ultraviolet light, ifnecessary. As such a reflecting film can be used, for example, a filmformed by vapor deposition of a metal such as aluminum or a dielectricmultilayer film in which a layer formed of a high-refractive-indexmaterial and a layer formed of a low-refractive-index material arealternately laminated. The reflecting film may be formed as eachprincipal surface of the optical filter, or may be formed as oneprincipal surface of the optical filter. When the reflecting film isformed in the former manner, the stress on the front side and that onthe back side are balanced, and that decreases the likelihood of warpingof the optical filter. When the reflecting film is a dielectricmultilayer film, a material, such as TiO₂, ZrO₂, Ta₂O₅, Nb₂O₅, ZnO, orIn₂O₃, having a refractive index of 1.7 to 2.5 is used as thehigh-refractive-index material. A material, such as SiO₂, Al₂O₃, orMgF₂, having a refractive index of 1.2 to 1.6 is used as thelow-refractive-index material. Examples of the method for forming thedielectric multilayer film include chemical vapor deposition (CVD),sputtering, and vacuum deposition.

The optical filters 1 a to 1 f are each disposed ahead (on the sidecloser to an object) of an imaging sensor, such as a CCD or CMOS, in animaging apparatus in order to, for example, allow the spectralsensitivity of the imaging sensor in the imaging apparatus toapproximate to the visual sensitivity of humans.

Further, as shown in FIG. 2 , a camera module 100 employing, forexample, the optical filter 1 a can be provided. The camera module 100includes, for example, a lens system 2, a low-pass filter 3, an imagingsensor 4, a circuit board 5, an optical filter support housing 7, and anoptical system housing 8 in addition to the optical filter 1 a. The rimof the optical filter 1 a is, for example, fitted to a ring-shapedrecessed portion adjacent to an opening formed in the middle of theoptical filter support housing 7. The optical filter support housing 7is fixed to the optical system housing 8. In the optical system housing8, the lens system 2, low-pass filter 3, and imaging sensor 4 aredisposed in this order along an optical axis. The imaging sensor 4 is,for example, a CCD or CMOS. After the ultraviolet and infrared portionsof light coming from an object are cut by the optical filter 1 a, theresultant light is focused by the lens system 2 and then goes throughthe low-pass filter 3 to enter the imaging sensor 4. An electricalsignal generated by the imaging sensor 4 is sent outside the cameramodule 100 by the circuit board 5.

In the camera module 100, the optical filter 1 a functions also as acover (protective filter) that protects the lens system 2. In this case,a sapphire substrate is desirably used as the transparent dielectricsubstrate 20 of the optical filter 1 a. Having high scratch-resistance,a sapphire substrate is desirably disposed, for example, on the externalside (the side opposite to the imaging sensor 4). The optical filter 1 aconsequently exhibits high scratch-resistance, for example, on externalcontact and has the optical characteristics (i) to (v) (and desirablyfurther has the optical characteristics (vi) to (xiii)). This eliminatesthe need to dispose an optical filter for cutting off infrared light orultraviolet light near the imaging sensor 4 and facilitates a reductionof the camera module 100 in profile. It should be noted that FIG. 2showing the camera module 100 is a schematic diagram illustrating anexample of, for example, the disposition of the parts, and describes anembodiment where the optical filter 1 a is used as a protective filter.As long as the optical filter 1 a functions as a protective filter, thecamera module employing the optical filter 1 a is not limited to the oneshown in FIG. 2 . If necessary, the low-pass filter 3 may be omitted oranother filter may be included.

EXAMPLES

The present invention will be described in more detail by examples. Thepresent invention is not limited to the examples given below. First,methods for evaluation of optical filters according to Examples andComparative Examples will be described.

<Measurement of Transmittance Spectra of Optical Filter>

Transmittance spectra shown upon incidence of light with wavelengths of300 nm to 1200 nm on the optical filters according to Examples andComparative Examples were measured using an ultraviolet-visiblespectrophotometer (manufactured by JASCO Corporation, product name:V-670). The incident angle of the light incident on the optical filterswas changed from 0° to 65° at 5° intervals to measure a transmittancespectrum at each angle.

<Measurement of Thickness of UV-IR-Absorbing Layer>

The thicknesses of the optical filters according to Examples andComparative Examples were measured with a digital micrometer. For eachoptical filter according to Example or Comparative Example having atransparent dielectric substrate made of, for example, glass, thethickness of the UV-IR-absorbing layer of the optical film wasdetermined by subtracting the thickness of the transparent glasssubstrate from the thickness of the optical filter measured with adigital micrometer.

Example 1

1.125 g of copper acetate monohydrate ((CH₃COO)₂Cu·H₂O) and 60 g oftetrahydrofuran (THF) were mixed, and the mixture was stirred for 3hours to obtain a copper acetate solution. To the obtained copperacetate solution was then added 0.412 g of PLYSURF A208N (manufacturedby DKS Co., Ltd.) which is a phosphoric acid ester compound, and themixture was stirred for 30 minutes to obtain a solution A. 10 g of THFwas added to 0.441 g of phenylphosphonic acid (C₆H₅PO(OH)₂)(manufactured by Nissan Chemical Industries, Ltd.), and the mixture wasstirred for 30 minutes to obtain a solution B-1. 10 g of THF was addedto 0.661 g of 4-bromophenylphosphonic acid (C₆H₄BrPO(OH)₂) (manufacturedby Tokyo Chemical Industry Co., Ltd.), and the mixture was stirred for30 minutes to obtain a solution B-2. Next, the solutions B-1 and B-2were mixed, and the mixture was stirred for 1 minute. 1.934 g ofmethyltriethoxysilane (MTES: CH₃Si(OC₂H₅)₃) (manufactured by Shin-EtsuChemical Co., Ltd.) and 0.634 g of tetraethoxysilane (TEOS: Si(OC₂H₅)₄)(manufactured by KISHIDA CHEMICAL Co., Ltd., special grade) were added,and the mixture was further stirred for 1 minute to obtain a solution B.The solution B was added to the solution A while the solution A wasstirred, and the mixture was stirred at room temperature for 1 minute.To the resultant solution was then added 25 g of toluene, and themixture was stirred at room temperature for 1 minute to obtain asolution C. This solution C was placed in a flask and subjected tosolvent removal using a rotary evaporator (manufactured by TokyoRikakikai Co., Ltd., product code: N-1110SF) under heating by means ofan oil bath (manufactured by Tokyo Rikakikai Co., Ltd., product code:OSB-2100). The temperature of the oil bath was controlled to 105° C. Asolution D which had been subjected to the solvent removal was thencollected from the flask. The solution D which is a dispersion of fineparticles of copper phenyl-based phosphonate (absorber) including copperphenylphosphonate and copper 4-bromophenylphosphonate was transparent,and the fine particles were well dispersed therein.

0.225 g of copper acetate monohydrate and 36 g of THF were mixed, andthe mixture was stirred for 3 hours to obtain a copper acetate solution.To the obtained copper acetate solution was then added 0.129 g ofPLYSURF A208N which is a phosphoric acid ester compound, and the mixturewas stirred for 30 minutes to obtain a solution E. 10 g of THF was addedto 0.144 g of n-butylphosphonic acid (C₄H₉PO(OH)₂) (manufactured byNippon Chemical Industrial Co., Ltd.), and the mixture was stirred for30 minutes to obtain a solution F. The solution F was added to thesolution E while the solution E was stirred, and the mixture was stirredat room temperature for 1 minute. To the resultant solution was thenadded 25 g of toluene, and the mixture was stirred at room temperaturefor 1 minute to obtain a solution G. This solution G was placed in aflask and subjected to solvent removal using a rotary evaporator underheating by means of an oil bath. The temperature of the oil bath wascontrolled to 105° C. A solution H which had been subjected to thesolvent removal was then collected from the flask. The solution H whichis a dispersion of fine particles of copper butylphosphonate wastransparent, and the fine particles were well dispersed therein.

To the solution D was added 2.200 g of a silicone resin (manufactured byShin-Etsu Chemical Co., Ltd., product name: KR-300), and the mixture wasstirred for 30 minutes to obtain a solution I. The solution H was addedto the solution I, and the mixture was stirred for 30 minutes to obtaina UV-IR-absorbing composition (solution J) according to Example 1. Forthe UV-IR-absorbing composition (solution J) according to Example 1, thecontents of the components are shown in Table 1 on a mass basis, and thecontents of the components and the percentage contents of the phosphonicacids are shown in Table 2 on an amount-of-substance basis. Thepercentage content of each phosphonic acid is determined by rounding avalue to one decimal place, and thus the sum of the percentage contentsmay not always be 100 mol %.

The UV-IR-absorbing composition according to Example 1 was applied witha dispenser to a 30 mm×30 mm central region of one principal surface ofa transparent glass substrate (manufactured by SCHOTT AG, product name:D 263) made of borosilicate glass and having dimensions of 76 mm×76mm×0.21 mm. A film was thus formed on the substrate. The thickness ofthe film was determined through trial and error so that the opticalfilter would have an average transmittance of about 1% in the wavelengthrange of 700 to 730 nm. When the UV-IR-absorbing composition was appliedto the transparent glass substrate, a frame having an openingcorresponding in dimensions to the region where the film-forming liquidwas applied was put on the transparent glass substrate to hold back thefilm-forming liquid and prevent the film-forming liquid from spreading.The amount of the film-forming liquid applied was adjusted, so that thefilm obtained had a desired thickness. Subsequently, the transparentglass substrate with the undried film was placed in an oven andheat-treated at 85° C. for 6 hours to cure the film. After that, thetransparent glass substrate with the film formed thereon was placed in athermo-hygrostat set at a temperature of 85° C. and a relative humidityof 85% for a 20-hour humidification treatment. An optical filteraccording to Example 1 including a UV-IR-absorbing layer formed on atransparent glass substrate was thus obtained. The humidificationtreatment was performed to promote hydrolysis and polycondensation ofthe alkoxysilanes contained in the UV-IR-absorbing composition appliedonto the transparent glass substrate and form a hard and dense matrix ofthe UV-IR-absorbing layer. The thickness of the UV-IR-absorbing layer ofthe optical filter according to Example 1 was 170 μm. Transmittancespectra shown by the optical filter according to Example 1 at incidentangles ranging from 0° to 65° were measured. The transmittance spectrashown thereby at incident angles of 0°, 40°, 50°, and 60° are shown inFIG. 3 . The results of observing the transmittance spectrum shown bythe optical filter according to Example 1 at an incident angle of 0° areshown in Tables 7 and 8. “Wavelength range in which transmittance is 78%or more” in Table 8 refers to a wavelength range which is in thewavelength range of 400 nm to 600 nm and in which the spectraltransmittance is 78% or more. “Wavelength range in which transmittanceis 1% or less” as to the infrared region properties in Table 8 refers toa wavelength range which is in the wavelength range of 700 nm to 1200 nmand in which the spectral transmittance is 1% or less. “Wavelength rangein which transmittance is 0.1% or less” as to the infrared regionproperties in Table 8 refers to a wavelength range which is in thewavelength range of 700 nm to 1200 nm and in which the spectraltransmittance is 0.1% or less. “Wavelength range in which transmittanceis 1% or less” as to the ultraviolet region properties in Table 8 refersto a wavelength range which is in the wavelength range of 300 nm to 400nm and in which the spectral transmittance is 1% or less. “Wavelengthrange in which transmittance is 0.1% or less” as to the ultravioletregion properties in Table 8 refers to a wavelength range which is inthe wavelength range of 300 nm to 400 nm and in which the spectraltransmittance is 0.1% or less. The same can be said in Tables 10, 12,14, 16, 18, and 20. Moreover, the results (incident angles: 0° to 65°)of observing the transmittance spectra shown by the optical filteraccording to Example 1 at incident angles of 0° and 30° to 65° (at 5°intervals) are shown in Tables 11 and 12.

Examples 2 to 15

UV-IR-absorbing compositions according to Examples 2 to 15 were preparedin the same manner as in Example 1, except that the amounts of thecompounds added were adjusted as shown in Table 1. Optical filtersaccording to Examples 2 to 15 were produced in the same manner as inExample 1, except that the UV-IR-absorbing compositions according toExamples 2 to 15 were used instead of the UV-IR-absorbing compositionaccording to Example 1 and that the thicknesses of the UV-IR-absorbinglayers were adjusted as shown in Table 1. The contents and percentagecontents of the phosphonic acids are shown in Table 2 on anamount-of-substance basis. The percentage content of each phosphonicacid is determined by rounding a value to one decimal place, and thusthe sum of the percentage contents may not always be 100 mol %.Transmittance spectra shown by the optical filter according to Example 2at incident angles ranging from 0° to 65° were measured. Thetransmittance spectra shown thereby at incident angles of 0°, 40°, 50°,and 60° are shown in FIG. 4 . The results of observing the transmittancespectrum shown by the optical filter according to Example 2 at anincident angle of 0° are shown in Tables 7 and 8. Moreover, the resultsof observing the transmittance spectra shown by the optical filteraccording to Example 2 at incident angles of 0° and 30° to 65° (at 5°intervals) are shown in Tables 13 and 14. Additionally, the results ofobserving the transmittance spectra shown by the optical filtersaccording to Examples 3 to 15 at an incident angle of 0° are shown inTables 7 and 8.

Example 16

The UV-IR-absorbing composition according to Example 2 was applied witha dispenser to a 30 mm×30 mm central region of one principal surface ofa transparent glass substrate (manufactured by SCHOTT AG, product name:D 263) made of borosilicate glass and having dimensions of 76 mm×76mm×0.21 mm. A film having a given thickness was thus formed on thesubstrate. When the UV-IR-absorbing composition was applied to thetransparent glass substrate, a frame having an opening corresponding indimensions to the region where the film-forming liquid was applied wasput on the transparent glass substrate to hold back the film-formingliquid and prevent the film-forming liquid from spreading. Next, thetransparent glass substrate with the undried film was placed in an ovenand heat-treated at 85° C. for 6 hours to cure the film. After that, thefilm was separated from the transparent glass substrate. The separatedfilm was placed in a thermo-hygrostat set at a temperature of 85° C. anda relative humidity of 85% for a 20-hour humidification treatment. Anoptical filter according to Example 16 consisting only of aUV-IR-absorbing layer was thus obtained. The thickness of thelight-absorbing layer alone was measured with a digital micrometer. Thethickness of the optical filter according to Example 16 turned out to be132 μm. Transmittance spectra shown by the optical filter according toExample 16 at incident angles ranging from 0° to 65° were measured. Thetransmittance spectra shown thereby at incident angles of 0°, 40°, 50°,and 60° are shown in FIG. 5 . The results of observing the transmittancespectrum shown by the optical filter according to Example 16 at anincident angle of 0° are shown in Tables 7 and 8. Moreover, the resultsof observing the transmittance spectra shown by the optical filteraccording to Example 16 at incident angles of 0° and 30° to 65° (at 5°intervals) are shown in Tables 15 and 16.

Example 17

The UV-IR-absorbing composition according to Example 2 was applied witha dispenser to a 30 mm×30 mm central region of one principal surface ofa transparent glass substrate (manufactured by SCHOTT AG, product name:D 263) made of borosilicate glass and having dimensions of 76 mm×76mm×0.21 mm. A film with about half the thickness of the film in Example2 was thus formed on the substrate. When the UV-IR-absorbing compositionwas applied to the transparent glass substrate, a frame having anopening corresponding in dimensions to the region where the film-formingliquid was applied was put on the transparent glass substrate to holdback the film-forming liquid and prevent the film-forming liquid fromspreading. Next, the transparent glass substrate with the undried filmwas placed in an oven and heat-treated at 85° C. for 6 hours to cure thefilm. Subsequently, the UV-IR-absorbing composition according to Example2 was applied with a dispenser to a 30 mm×30 mm central region of theother principal surface of the transparent glass substrate. A film withabout half the thickness of the thickness of the film in Example 2 wasthus formed on the substrate. When the UV-IR-absorbing composition wasapplied to the transparent glass substrate, a frame having an openingcorresponding in dimensions to the region where the film-forming liquidwas applied was put on the transparent glass substrate to hold back thefilm-forming liquid and prevent the film-forming liquid from spreading.Next, the transparent glass substrate with the undried film was placedin an oven and heat-treated at 85° C. for 6 hours to cure the film.Then, the transparent glass substrate with the above films formed onboth principal surfaces thereof was placed in a thermo-hygrostat set ata temperature of 85° C. and a relative humidity of 85% for a 20-hourhumidification treatment. An optical filter according to Example 17 inwhich UV-IR-absorbing layers were formed on both sides of a transparentglass substrate was thus obtained. The sum of the thicknesses of theUV-IR-absorbing layers formed on both sides of the transparent glasssubstrate was 193 μm. Transmittance spectra shown by the optical filteraccording to Example 17 at incident angles ranging from 0° to 65° weremeasured. The transmittance spectra shown thereby at incident angles of0°, 40°, 50°, and 60° are shown in FIG. 6 . The results of observing thetransmittance spectrum shown by the optical filter according to Example17 at an incident angle of 0° are shown in Tables 7 and 8. Moreover, theresults of observing the transmittance spectra shown by the opticalfilter according to Example 17 at incident angles of 0° and 30° to 65°(at 5° intervals) are shown in Tables 17 and 18.

Example 18

An optical filter according to Example 18 in which UV-IR-absorbinglayers were formed on both sides of a transparent glass substrate wasproduced in the same manner as in Example 17, except that a transparentglass substrate (manufactured by SCHOTT AG, product name: D 263) made ofborosilicate glass and having dimensions of 76 mm×76 mm×0.07 mm was usedinstead of the transparent glass substrate as used in Example 17. Thesum of the thicknesses of the UV-IR-absorbing layers formed on bothsides of the transparent glass substrate was 183 μm. Transmittancespectra shown by the optical filter according to Example 18 at incidentangles ranging from 0° to 65° were measured. The transmittance spectrashown thereby at incident angles of 0°, 40°, 50°, and 60° are shown inFIG. 7 . The results of observing the transmittance spectrum shown bythe optical filter according to Example 18 at an incident angle of 0°are shown in Tables 7 and 8. The results of observing the transmittancespectra shown by the optical filter according to Example 18 at incidentangles of 0° and 30° to 65° (at 5° intervals) are shown in Tables 19 and20.

Example 19

A UV-IR-absorbing composition according to Example 19 was prepared inthe same manner as in Example 1, except that PLYSURF A208F (manufacturedby DKS Co., Ltd.) was used as a phosphoric acid ester compound insteadof PLYSURF A208N and that the amounts of the compounds added wereadjusted as shown in Table 1. An optical filter according to Example 19was produced in the same manner as in Example 1, except that theUV-IR-absorbing composition according to Example 19 was used instead ofthe UV-IR-absorbing composition according to Example 1 and that thethickness of the UV-IR-absorbing layer was adjusted to 198 μm.Transmittance spectra shown by the optical filter according to Example19 were measured, and the results of observing the transmittancespectrum shown thereby at an incident angle of 0° are shown in Tables 7and 8.

Example 20

A UV-IR-absorbing composition according to Example 20 was prepared inthe same manner as in Example 1, except that 4-fluorophenylphosphonicacid (C₆H₄FPO(OH)₂) (manufactured by Tokyo Chemical Industry Co., Ltd.)was used instead of 4-bromophenylphosphonic acid and that the amounts ofthe compounds added were adjusted as shown in Table 1. An optical filteraccording to Example 20 was produced in the same manner as in Example 1,except that the UV-IR-absorbing composition according to Example 20 wasused instead of the UV-IR-absorbing composition according to Example 1and that the thickness of the UV-IR-absorbing layer was adjusted to 168μm. Transmittance spectra shown by the optical filter according toExample 20 were measured, and the results of observing the transmittancespectrum shown thereby at an incident angle of 0° are shown in Tables 7and 8.

Example 21

An optical filter according to Example 21 was produced in the samemanner as in Example 2, except that a 100-μm-thick infrared-absorbingglass substrate was used instead of the transparent glass substrate asused in Example 2 and that the thickness of the UV-IR-absorbing layerwas adjusted to 76 μm. This infrared-absorbing glass substrate containscopper and has a transmittance spectrum shown in FIG. 8A. Atransmittance spectrum shown by the optical filter according to Example21 at an incident angle of 0° was measured. The result is shown in FIG.8B. Moreover, the results of observing the transmittance spectrum shownby the optical filter according to Example 21 at an incident angle of 0°are shown in Tables 7 and 8.

Examples 22 to 37

Optical filters according to Examples 22 to 37 were each produced in thesame manner as in Example 2, except that the conditions of thehumidification treatment of the dried film were changed as shown inTable 3 and that the thickness of the UV-IR-absorbing layer was adjustedas shown in Table 3. Transmittance spectra shown by the optical filtersaccording to Examples 22 to 24 at an incident angle of 0° were measured.The results are separately shown in FIG. 9 to FIG. 11 . Moreover, theresults of observing the transmittance spectra shown by the opticalfilters according to Examples 22 to 24 at an incident angle of 0° areshown in Tables 7 and 8. Transmittance spectra shown by the opticalfilters according to Examples 25 to 37 were measured, and the results ofobserving the transmittance spectra shown thereby at an incident angleof 0° are shown in Tables 7 and 8.

Example 38

An optical filter according to Example 38 was produced in the samemanner as in Example 2, except that a 0.3-mm-thick sapphire substratewas used instead of the transparent glass substrate as used in Example 2and that the thickness of the UV-IR-absorbing layer was adjusted to 168μm. A transmittance spectrum shown by the optical filter according toExample 38 at an incident angle of 0° was measured. The result is shownin FIG. 12 . The results of observing the transmittance spectrum shownby the optical filter according to Example 38 at an incident angle of 0°are shown in Tables 7 and 8.

Comparative Example 1

A solution D (dispersion of fine particles of copper phenyl-basedphosphonate) according to Comparative Example 1 was prepared in the samemanner as in Example 1, except that the amounts of the compounds addedwere adjusted as shown in Tables 4 and 5. To the solution D according toComparative Example 1 was added 2.200 g of a silicone resin(manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300),and the mixture was stirred for 30 minutes to obtain a UV-IR-absorbingcomposition according to Comparative Example 1. An optical filteraccording to Comparative Example 1 was produced in the same manner as inExample 1, except that the UV-IR-absorbing composition according toComparative Example 1 was used instead of the UV-IR-absorbingcomposition according to Example 1 and that the thickness of theUV-IR-absorbing layer was adjusted to 126 μm. Transmittance spectrashown by the optical filter according to Comparative Example 1 weremeasured, and the results of observing the transmittance spectrum shownthereby at an incident angle of 0° are shown in Tables 9 and 10.Moreover, based on the results of the measurement of the transmittancespectrum shown by the optical filter according to Comparative Example 1at an incident angle of 0°, a transmittance spectrum was calculated onthe assumption that the thickness of the UV-IR-absorbing layer of theoptical filter according to Comparative Example 1 was changed to 200 μm.The results of observing this transmittance spectrum are shown in Tables9 and 10 as Comparative Calculation Example 1.

Comparative Example 2

A solution D (dispersion of fine particles of copper phenyl-basedphosphonate) according to Comparative Example 2 was prepared in the samemanner as in Example 1, except that the amounts of the compounds addedwere adjusted as shown in Tables 4 and 5. To the solution D according toComparative Example 2 was added 4.400 g of a silicone resin(manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300),and the mixture was stirred for 30 minutes to obtain a UV-IR-absorbingcomposition according to Comparative Example 2. An optical filteraccording to Comparative Example 2 was produced in the same manner as inExample 1, except that the UV-IR-absorbing composition according toComparative Example 2 was used instead of the UV-IR-absorbingcomposition according to Example 1, that the thickness of theUV-IR-absorbing layer was adjusted to 217 μm, and that the conditions ofthe heat treatment for curing the film and conditions of thehumidification treatment were changed as shown in Table 6. Transmittancespectra shown by the optical filter according to Comparative Example 2were measured, and the results of observing the transmittance spectrumshown thereby at an incident angle of 0° are shown in Tables 9 and 10.Moreover, based on the results of the measurement of the transmittancespectrum shown by the optical filter according to Comparative Example 2at an incident angle of 0°, a transmittance spectrum was calculated onthe assumption that the thickness of the UV-IR-absorbing layer of theoptical filter according to Comparative Example 2 was changed to 347 μm.The results of observing this transmittance spectrum are shown in Tables9 and 10 as Comparative Calculation Example 2.

Comparative Example 3

1.125 g of copper acetate monohydrate and 60 g of THF were mixed, andthe mixture was stirred for 3 hours to obtain a copper acetate solution.To the obtained copper acetate solution was then added 0.624 g ofPLYSURF A208F (manufactured by DKS Co., Ltd.), and the mixture wasstirred for 30 minutes to obtain a solution A. 10 g of THF was added to0.832 g of phenylphosphonic acid (manufactured by Nissan ChemicalIndustries, Ltd.), and the mixture was stirred for 30 minutes to obtaina solution B-1. 1.274 g of MTES (manufactured by Shin-Etsu Chemical Co.,Ltd.) and 1.012 g of TEOS (manufactured by KISHIDA CHEMICAL Co., Ltd.,special grade) were added to the solution B-1, and the mixture wasfurther stirred for 1 minute to obtain a solution B. The solution B wasadded to the solution A while the solution A was stirred, and themixture was stirred at room temperature for 1 minute. To the resultantsolution was then added 25 g of toluene, and the mixture was stirred atroom temperature for 1 minute to obtain a solution C. This solution Cwas placed in a flask and subjected to solvent removal using a rotaryevaporator (manufactured by Tokyo Rikakikai Co., Ltd., product code:N-1110SF) under heating by means of an oil bath (manufactured by TokyoRikakikai Co., Ltd., product code: OSB-2100). The temperature of the oilbath was controlled to 105° C. A solution D according to ComparativeExample 3 which had been subjected to the solvent removal was thencollected from the flask. The solution D (dispersion of fine particlesof copper phenylphosphonate) according to Comparative Example 3 wastransparent, and the fine particles were well dispersed therein.

To the solution D according to Comparative Example 3 was added 4.400 gof a silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd.,product name: KR-300), and the mixture was stirred for 30 minutes toobtain a UV-IR-absorbing composition according to Comparative Example 3.An optical filter according to Comparative Example 3 was produced in thesame manner as in Example 1, except that the UV-IR-absorbing compositionaccording to Comparative Example 3 was used instead of theUV-IR-absorbing composition according to Example 1, that the thicknessof the UV-IR-absorbing layer was adjusted to 198 μm, and that theconditions of the heat treatment for curing the film were changed asshown in Table 6. Transmittance spectra shown by the optical filteraccording to Comparative Example 3 were measured, and the results ofobserving the transmittance spectrum shown thereby at an incident angleof 0° are shown in Tables 9 and 10. Moreover, based on the results ofthe measurement of the transmittance spectrum shown by the opticalfilter according to Comparative Example 3, a transmittance spectrum wascalculated on the assumption that the thickness of the UV-IR-absorbinglayer of the optical filter according to Comparative Example 3 waschanged to 303 μm. The results of observing this transmittance spectrumare shown in Tables 9 and 10 as Comparative Calculation Example 3.

Comparative Example 4

1.125 g of copper acetate monohydrate and 60 g of THF were mixed, andthe mixture was stirred for 3 hours to obtain a copper acetate solution.To the obtained copper acetate solution was then added 0.891 g ofPLYSURF A208F which is a phosphoric acid ester compound, and the mixturewas stirred for 30 minutes to obtain a solution E. 10 g of THF was addedto 0.670 g of n-butylphosphonic acid (manufactured by Nippon ChemicalIndustrial Co., Ltd.), and the mixture was stirred for 30 minutes toobtain a solution F. The solution F was added to the solution E whilethe solution E was stirred, and the mixture was stirred at roomtemperature for 1 minute. To the resultant solution was then added 25 gof toluene, and the mixture was stirred at room temperature for 1 minuteto obtain a solution G. This solution G was placed in a flask andsubjected to solvent removal using a rotary evaporator under heating bymeans of an oil bath. The temperature of the oil bath was controlled to105° C. A solution H according to Comparative Example 4 which had beensubjected to the solvent removal was then collected from the flask. Thesolution H which is a dispersion of fine particles of copperbutylphosphonate was transparent, and the fine particles were welldispersed therein.

To the solution H according to Comparative Example 4 was added 4.400 gof a silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd.,product name: KR-300), and the mixture was stirred for 30 minutes toobtain a UV-IR-absorbing composition according to Comparative Example 4.An optical filter according to Comparative Example 4 was produced in thesame manner as in Comparative Example 2, except that the UV-IR-absorbingcomposition according to Comparative Example 4 was used instead of theUV-IR-absorbing composition according to Comparative Example 2, that thethickness of the UV-IR-absorbing layer was adjusted to 1002 μm, and thatthe humidification treatment of the film was not performed.Transmittance spectra shown by the optical filter according toComparative Example 4 were measured, and the results of observing thetransmittance spectrum shown thereby at an incident angle of 0° areshown in Tables 9 and 10. Moreover, based on the results of themeasurement of the transmittance spectrum shown by the optical filteraccording to Comparative Example 4 at an incident angle of 0°,transmittance spectra were calculated on the assumption that thethickness of the UV-IR-absorbing layer of the optical filter accordingto Comparative Example 4 was changed to 1216 μm and 385 μm. The resultsof observing these transmittance spectra are shown in Tables 9 and 10 asComparative Calculation Example 4-A and Comparative Calculation Example4-B.

Comparative Example 5

An optical filter according to Comparative Example 5 was produced in thesame manner as in Example 2, except that the thickness of theUV-IR-absorbing layer was adjusted to 191 μm and that the humidificationtreatment of the film was not performed. Transmittance spectra shown bythe optical filter according to Comparative Example 5 were measured, andthe results of observing the transmittance spectrum shown thereby at anincident angle of 0° are shown in Tables 9 and 10. Based on the resultsof the measurement of the transmittance spectrum shown by the opticalfilter according to Comparative Example 5 at an incident angle of 0°, atransmittance spectrum was calculated on the assumption that thethickness of the UV-IR-absorbing layer of the optical filter accordingto Comparative Example 5 was changed to 148 μm. The results of observingthis transmittance spectrum are shown in Tables 9 and 10 as ComparativeCalculation Example 5.

Comparative Examples 6 and 7

Optical filters according to Comparative Examples 6 and 7 were eachproduced in the same manner as in Example 2, except that the thicknessof the UV-IR-absorbing layer was adjusted as shown in Table 9 and thatthe humidification treatment of the film was adjusted as shown in Table6. Transmittance spectra shown by the optical filters according toComparative Examples 6 and 7 were measured, and the results of observingthe transmittance spectra shown thereby at an incident angle of 0° areshown in Tables 9 and 10. Based on the results of the measurement of thetransmittance spectrum shown by the optical filter according toComparative Example 6 at an incident angle of 0°, a transmittancespectrum was calculated on the assumption that the thickness of theUV-IR-absorbing layer of the optical filter according to ComparativeExample 6 was changed to 155 μm. The results of observing thistransmittance spectrum are shown in Tables 9 and 10 as ComparativeCalculation Example 6. Additionally, based on the results of themeasurement of the transmittance spectrum shown by the optical filteraccording to Comparative Example 7 at an incident angle of 0°, atransmittance spectrum was calculated on the assumption that thethickness of the UV-IR-absorbing layer of the optical filter accordingto Comparative Example 7 was changed to 161 μm. The results of observingthis transmittance spectrum are shown in Tables 9 and 10 as ComparativeCalculation Example 7.

Comparative Example 8

A solution D (dispersion of fine particles of copper phenyl-basedphosphonate) according to Comparative Example 8 was prepared in the samemanner as in Comparative Example 1. 0.225 g of copper acetatemonohydrate and 36 g of THF were mixed, and the mixture was stirred for3 hours to obtain a copper acetate solution. To the obtained copperacetate solution was then added 0.178 g of PLYSURF A208F (manufacturedby DKS Co., Ltd.) which is a phosphoric acid ester compound, and themixture was stirred for 30 minutes to obtain a solution E. 10 g of THFwas added to 0.134 g of n-butylphosphonic acid (manufactured by NipponChemical Industrial Co., Ltd.), and the mixture was stirred for 30minutes to obtain a solution F. The solution F was added to the solutionE while the solution E was stirred, and the mixture was stirred at roomtemperature for 1 minute. To the resultant solution was then added 25 gof toluene, and the mixture was stirred at room temperature for 1 minuteto obtain a solution G. This solution G was placed in a flask andsubjected to solvent removal using a rotary evaporator under heating bymeans of an oil bath. The temperature of the oil bath was controlled to105° C. A solution H according to Comparative Example 8 which had beensubjected to the solvent removal was then collected from the flask. Tothe solution D according to Comparative Example 8 was added 2.200 g of asilicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., productname: KR-300), and the mixture was stirred for 30 minutes to obtain asolution I according to Comparative Example 8. The solution H accordingto Comparative Example 8 was added to the solution I according toComparative Example 8, and the mixture was stirred. Aggregation ofcopper phosphonate particles occurred and a UV-IR-absorbing compositionhaving a high transparency could not be obtained.

Comparative Example 9

An attempt to prepare a UV-IR-absorbing composition containingn-butylphosphonic acid, as the only phosphonic acid, in an amount shownin Table 4 and no alkoxysilane monomer resulted in aggregation of copperphosphonate particles, and a homogeneous UV-IR-absorbing compositionhaving a high transparency could not be obtained.

According to Table 7, the optical filters according to Examples 1 to 38have the optical characteristics (i) to (vii). Moreover, according toTables 11, 13, 15, 17, and 19, the optical filters according to Examples1, 2, and 16 to 18 further have the optical characteristics (viii) to(xi). Furthermore, according to other results (incident angles: 0° to65°) (not shown) of the transmittance spectrum measurement of theoptical filters according to Examples 3 to 15 and 19 to 38, the opticalfilters according to these Examples also further have the opticalcharacteristics (viii) to (xi).

According to Table 9, the optical filter according to ComparativeExample 1 does not have the optical characteristics (ii), (vi), and(vii), and does not have the desired properties in the infrared region.Additionally, Comparative Calculation Example 1 indicates that anincrease in thickness of the UV-IR-absorbing layer can improve theinfrared region properties but shortens the first IR cut-off wavelength,resulting in failure to achieve the optical characteristic (iv). Theseindicate that an optical filter having all the optical characteristics(i) to (v) cannot be produced with the use of the UV-IR-absorbingcomposition according to Comparative Example 1. Likewise, the resultsfor Comparative Example 2 and Comparative Calculation Example 2 and theresults for Comparative Example 3 and Comparative Calculation Example 3in Table 9 indicate that an optical filter having all the opticalcharacteristics (i) to (v) cannot be produced with the use of theUV-IR-absorbing compositions according to Comparative Examples 2 and 3.

According to Table 9, the optical filter according to ComparativeExample 4 does not have the optical characteristics (iii) and (v), anddoes not have the desired properties in the ultraviolet region.Additionally, Comparative Calculation Example 4-A indicates that anincrease in thickness of the UV-IR-absorbing layer can achieve theoptical characteristics (iii) and (v) but makes it difficult to achievethe optical characteristic (i). Comparative Calculation Example 4-Bindicates that a decrease in thickness of the UV-IR-absorbing layer canimprove the optical characteristic (i) but much worsens the opticalcharacteristics (iii) and (v), and also increases the maximumtransmittance in the wavelength range of 750 to 1080 nm. These indicatethat an optical filter having all the optical characteristics (i) to (v)cannot be produced with the use of the UV-IR-absorbing compositionaccording to Comparative Example 4.

According to Table 9, the optical filter according to ComparativeExample 5 does not have the optical characteristics (i) and (iv).Comparative Calculation Example 5 indicates that a decrease in thicknessof the UV-IR-absorbing layer increases the average transmittance in thewavelength range of 450 to 600 nm but does not change the IR cut-offwavelength very much, and also increases the maximum transmittance inthe wavelength range of 750 to 1080 nm. These indicate that an opticalfilter having all the optical characteristics (i) to (v) cannot beproduced by the method for producing the optical filter according toComparative Example 5. It is indicated that the humidification treatmentnot only promotes the hydrolysis and polycondensation of thealkoxysilane monomers in the UV-IR-absorbing composition to promote thecuring of the UV-IR-absorbing layer, but also affects a transmittancespectrum of the optical filter.

According to Table 9, the optical filter according to ComparativeExample 6 does not have the optical characteristic (iv). ComparativeCalculation Example 6 indicates that a decrease in thickness of theUV-IR-absorbing layer can increase the IR cut-off wavelength but alsoincreases the maximum transmittance in the wavelength range of 750 to1080 nm. These indicate that an optical filter having all the opticalcharacteristics (i) to (v) cannot be produced by the method forproducing the optical filter according to Comparative Example 6. Inparticular, it is indicated that the humidification treatment conditionsin Comparative Example 6 are insufficient.

According to Table 9, the optical filter according to ComparativeExample 7 does not have the optical characteristics (i) and (iv).Comparative Calculation Example 7 indicates that a decrease in thicknessof the UV-IR-absorbing layer can increase the IR cut-off wavelength butalso increases the maximum transmittance in the wavelength range of 750to 1080 nm. These indicate that an optical filter having all the opticalcharacteristics (i) to (v) cannot be produced by the method forproducing the optical filter according to Comparative Example 7. Inparticular, it is indicated that the humidification treatment conditionsin Comparative Example 7 are insufficient.

As shown in Table 2, the UV-IR-absorbing composition according toExample 3 has the highest percentage content of n-butylphosphonic acidand the UV-IR-absorbing composition according to Example 5 has thelowest percentage content of n-butylphosphonic acid among theUV-IR-absorbing compositions according to Examples 3 to 5. This fact andTable 8 indicate that an increase in the percentage content of thealkyl-based phosphonic acid in the UV-IR-absorbing composition expandsthe wavelength range where the spectral transmittance is 1% or lesswithin the wavelength range of 700 to 1200 nm to the long-wavelengthside and expands the wavelength range where the spectral transmittanceis 0.1% or less within the wavelength range of 700 to 1200 nm to thelong-wavelength side. The same can be said for Examples 6 to 8, forExamples 9 and 10, and for Examples 11 to 15.

As shown in Table 2, the UV-IR-absorbing composition according toExample 11 has the highest percentage content of n-butylphosphonic acid,the UV-IR-absorbing composition according to Example 12 has the secondhighest percentage content of n-butylphosphonic acid, theUV-IR-absorbing composition according to Example 13 has the thirdhighest percentage content of n-butylphosphonic acid, and theUV-IR-absorbing composition according to Example 15 has the lowestpercentage content of n-butylphosphonic acid among the UV-IR-absorbingcompositions according to Examples 11 to 15. According to the resultsfor Examples 11 to 15 in Table 7, Example 11 is the lowest, Example 12is the second lowest, Example 13 is the third lowest, and Example 15 isthe highest in terms of the maximum transmittance of the optical filterin the wavelength range of 1000 to 1100 nm and the maximum transmittanceof the optical filter in the wavelength range of 1100 to 1200 nm. Theseindicate that the performance of shielding against light with awavelength in the infrared region is improved by increasing thepercentage content of the alkyl-based phosphonic acid in theUV-IR-absorbing composition within the given range.

As shown in Table 2, the UV-IR-absorbing composition according toExample 7 has the highest percentage content of 4-bromophenylphosphonicacid and the UV-IR-absorbing composition according to Example 13 has thelowest percentage content of 4-bromophenylphosphonic acid among theUV-IR-absorbing compositions according to Examples 7, 10, and 13.According to the results for Examples 7, 10, and 13 in Table 7, thehigher percentage content of 4-bromophenylphosphonic acid theUV-IR-absorbing composition has, the greater the UV cut-off wavelengthis. This indicates that the optical characteristics of the opticalfilter can be optimized by adjusting the percentage content of4-bromophenylphosphonic acid in the UV-IR-absorbing composition.

The UV-IR-absorbing compositions using which the optical filtersaccording to Examples 22 to 37 and Comparative Examples 5 to 7 wereproduced were prepared in the same manner as for the UV-IR-absorbingcomposition according to Example 2. However, as shown in Tables 7 to 10,the optical filters according to these Examples and these ComparativeExamples have different optical characteristics from those of theoptical filter according to Example 2. As described above, thehumidification treatment was performed in order to promote thehydrolysis and polycondensation of the alkoxysilanes contained in theUV-IR-absorbing compositions. Depending on the conditions of thehumidification treatment, the average transmittance in the wavelengthrange of 450 to 600 nm and the IR cut-off wavelength differed among theoptical filters according to these Examples and these ComparativeExamples.

According to the results for Comparative Calculation Examples 5 to 7 inTable 9, the UV cut-off wavelength can be adjusted by changing thethickness of the UV-IR-absorbing layer. However, when any of the methodsfor producing the optical filters according to Comparative Examples 5 to7 are employed, it is difficult to keep an IR cut-off wavelength withinthe desired range and satisfy the optical characteristics (i) to (xi)exclusive of the optical characteristics related to the IR cut-offwavelength as well. Thus, the amount of water vapor (water vaporexposure amount) in an environment to which the treated article had beenexposed in the humidification treatment in each of Examples or each ofsome Comparative Examples was determined as follows. The results areshown in Tables 3 and 6. A saturated water vapor pressure e [hPa] at atemperature t [° C.] was determined by Tetens' equation:e=6.11×10^((7.5t/(t+237.3))). A water vapor concentration ρv [g/m³] wasdetermined using the saturated water vapor pressure e [hPa] and arelative humidity φ [%] by the following equation:ρv=217×e×φ/(t+273.15). “Amount of water vapor×hour [mol/m³·hour]” wasdefined as the water vapor exposure amount. As shown in Tables 3 and 6,it is indicated that when the temperature is 60° C. or more, thehumidification treatment performed at a relative humidity of 70% or morefor a treatment time of 1 hour or more results in achievement of goodoptical characteristics. These treatment conditions correspond to theconditions for achieving a water vapor exposure amount of 5.0[mol/m³·hour] or more. It is indicated that extending the treatment timeto ensure a similar water vapor exposure amount results in achievementof good optical characteristics when the temperature is as low as 40° C.and the relative humidity is 70% in the humidification treatment or whenthe temperature is 60° C. and the relative humidity is as low as 40% inthe humidification treatment. These results indicate that thehumidification treatment is desirably performed for a short period oftime in an environment at a temperature of 60° C. or more and a relativehumidity of 70% or more to efficiently provide good opticalcharacteristics for the optical filter.

TABLE 1 Material used and amount [g] thereof Solution H (compositioncontaining copper alkyl-based phosphonate Thick- Alkyl- ness Solution D(composition containing copper phenyl-based phosphonate) based [μm]Phenyl-based phosphonic acid phosphonic of Phenyl- 4-bromo- 4-fluoro-Copper acid Copper UV- phos- phenyl- phenyl- Phosphoric Alkoxysilaneacetate n-butyl- Phosphoric acetate Matrix IR- phonic phosphonicphosphonic acid ester monomer mono- phosphonic acid ester mono-(silicone absorb- acid acid acid A208N A208F MTES TEOS hydrate acidA208N A208F hydrate resin) ing [g] [g] [g] [g] [g] [g] [g] [g] [g] [g][g] [g] [g] layer Ex. 1 0.441 0.661 — 0.412 — 1.934 0.634 1.125 0.1440.129 — 0.225 2.200 170 Ex. 2 0.176 1.058 — 0.412 — 2.166 0.710 1.1250.289 0.257 — 0.450 2.200 135 Ex. 3 0.176 1.058 — 0.412 — 2.166 0.7101.125 0.433 0.386 — 0.675 1.257 178 Ex. 4 0.176 1.058 — 0.412 — 2.1660.710 1.125 0.289 0.257 — 0.450 1.257 154 Ex. 5 0.176 1.058 — 0.412 —2.166 0.710 1.125 0.144 0.129 — 0.225 1.257 143 Ex. 6 0.176 1.058 —0.412 — 2.166 0.710 1.125 0.433 0.386 — 0.675 2.200 212 Ex. 7 0.1761.058 — 0.412 — 2.166 0.710 1.125 0.289 0.257 — 0.450 2.200 182 Ex. 80.176 1.058 — 0.412 — 2.166 0.710 1.125 0.144 0.129 — 0.225 2.200 162Ex. 9 0.265 0.925 — 0.412 — 2.166 0.710 1.125 0.433 0.386 — 0.675 2.200193 Ex. 10 0.265 0.925 — 0.412 — 2.166 0.710 1.125 0.289 0.257 — 0.4502.200 152 Ex. 11 0.441 0.661 — 0.412 — 2.166 0.710 1.125 0.433 0.386 —0.675 2.200 180 Ex. 12 0.441 0.661 — 0.412 — 2.166 0.710 1.125 0.3610.322 — 0.563 2.200 171 Ex. 13 0.441 0.661 — 0.412 — 2.166 0.710 1.1250.289 0.257 — 0.450 2.200 158 Ex. 14 0.441 0.661 — 0.412 — 2.166 0.7101.125 0.216 0.193 — 0.338 2.200 152 Ex. 15 0.441 0.661 — 0.412 — 2.1660.710 1.125 0.144 0.129 — 0.225 2.200 140 Ex. 16 0.176 1.058 — 0.412 —2.166 0.710 1.125 0.289 0.257 — 0.450 2.200 132 Ex. 17 0.176 1.058 —0.412 — 2.166 0.710 1.125 0.289 0.257 — 0.450 2.200 193 Ex. 18 0.1761.058 — 0.412 — 2.166 0.710 1.125 0.433 0.386 — 0.675 2.200 183 Ex. 190.176 1.058 — — 0.412 2.166 0.710 1.125 0.433 — 0.386 0.675 2.200 198Ex. 20 0.441 — 0.476 0.412 — 2.166 0.710 1.125 0.289 0.257 — 0.450 2.200168 Ex. 21 0.176 1.058 — 0.412 — 2.166 0.710 1.125 0.289 0.257 — 0.4502.200  76 Ex. 38 0.176 1.058 — 0.412 — 2.166 0.710 1.125 0.289 0.257 —0.450 2.200 168

TABLE 2 Amount- Amount- Solution H of- of- Solution D (compositioncontaining (composition containing substance substance copperphenyl-based phosphonate) copper alkyl-based ratio of ratio ofPhenyl-based phosphonate halo- phenyl- phosphonic acid Alkyl- genatedbased Halo- based phenyl- phos- Percentage content (mol %) gen-phosphonic phosphonic phonic of each phosphonic acid with Phenyl- atedCopper acid Copper acid to acid to respect to total phosphonic acidsphos- phos- Alkoxysilane acetate n-butyl- acetate phenyl- alkyl-basedPhenyl- 4-bromo- phonic phonic monomer mono- phosphonic mono- phos-phos- phos- phenyl n-butyl acid acid MTES TEOS hydrate acid hydratephonic phonic phonic phosphonic phosphonic [mol] [mol] [mol] [mol] [mol][mol] [mol] acid acid acid acid acid Ex. 1 0.00279 0.00279 0.01080.00304 0.00563 0.00104 0.00113 1.0 5.4 42.1 42.1 15.7 Ex. 2 0.001120.00446 0.0121 0.00341 0.00563 0.00209 0.00225 4.0 2.7 14.6 58.1 27.2Ex. 3 0.00112 0.00446 0.0121 0.00341 0.00563 0.00313 0.00338 4.0 1.812.9 51.2 35.9 Ex. 4 0.00112 0.00446 0.0121 0.00341 0.00563 0.002090.00225 4.0 2.7 14.6 58.1 27.2 Ex. 5 0.00112 0.00446 0.0121 0.003410.00563 0.00104 0.00113 4.0 5.4 16.9 67.4 15.7 Ex. 6 0.00112 0.004460.0121 0.00341 0.00563 0.00313 0.00338 4.0 1.8 12.9 51.2 35.9 Ex. 70.00112 0.00446 0.0121 0.00341 0.00563 0.00209 0.00225 4.0 2.7 14.6 58.127.2 Ex. 8 0.00112 0.00446 0.0121 0.00341 0.00563 0.00104 0.00113 4.05.4 16.9 67.4 15.7 Ex. 9 0.00167 0.00390 0.0121 0.00341 0.00563 0.003130.00338 2.3 1.8 19.2 44.8 36.0 Ex. 10 0.00167 0.00390 0.0121 0.003410.00563 0.00209 0.00225 2.3 2.7 21.8 50.9 27.3 Ex. 11 0.00279 0.002790.0121 0.00341 0.00563 0.00313 0.00338 1.0 1.8 32.0 32.0 35.9 Ex. 120.00279 0.00279 0.0121 0.00341 0.00563 0.00261 0.00282 1.0 2.1 34.1 34.131.9 Ex. 13 0.00279 0.00279 0.0121 0.00341 0.00563 0.00209 0.00225 1.02.7 36.4 36.4 27.2 Ex. 14 0.00279 0.00279 0.0121 0.00341 0.00563 0.001570.00169 1.0 3.6 39.0 39.0 22.0 Ex. 15 0.00279 0.00279 0.0121 0.003410.00563 0.00104 0.00113 1.0 5.4 42.1 42.1 15.7 Ex. 16 0.00112 0.004460.0121 0.00341 0.00563 0.00209 0.00225 4.0 2.7 14.6 58.1 27.2 Ex. 170.00112 0.00446 0.0121 0.00341 0.00563 0.00209 0.00225 4.0 2.7 14.6 58.127.2 Ex. 18 0.00112 0.00446 0.0121 0.00341 0.00563 0.00313 0.00338 4.01.8 12.9 51.2 35.9 Ex. 19 0.00112 0.00446 0.0121 0.00341 0.00563 0.003130.00338 4.0 1.8 12.9 51.2 35.9 Ex. 20 0.00279 0.00271 0.0121 0.003410.00563 0.00209 0.00225 1.0 2.6 36.8 35.7 27.5 Ex. 21 0.00112 0.004460.0121 0.00341 0.00563 0.00209 0.00225 4.0 2.7 14.6 58.1 27.2 Ex. 380.00112 0.00446 0.0121 0.00341 0.00563 0.00209 0.00225 4.0 2.7 14.6 58.127.2

TABLE 3 Thick- ness Water vapor [μm] of Conditions of Conditions ofexposure UV-IR- heat treatment humidification amount absorbing forcuring film treatment [mol/m³ · hour] layer Examples 85° C.: 6 hours 85°C. 85% 332.3 See 1 to 21 RH: 20 hours Table 1 Example 22 85° C.: 6 hours85° C. 85% 16.6 179 RH: 1 hour Example 23 85° C.: 6 hours 85° C. 85%33.2 177 RH: 2 hours Example 24 85° C.: 6 hours 85° C. 85% 997.2 170 RH:60 hours Example 25 85° C.: 6 hours 60° C. 90% 6.5 170 RH: 1 hourExample 26 85° C.: 6 hours 60° C. 90% 13.0 175 RH: 2 hours Example 2785° C.: 6 hours 60° C. 90% 129.8 174 RH: 20 hours Example 28 85° C.: 6hours 60° C. 90% 389.4 168 RH: 60 hours Example 29 85° C.: 6 hours 60°C. 70% 5.1 175 RH: 1 hour Example 30 85° C.: 6 hours 60° C. 70% 10.1 178RH: 2 hours Example 31 85° C.: 6 hours 60° C. 70% 101.0 160 RH: 20 hoursExample 32 85° C.: 6 hours 60° C. 70%: 303.0 164 60 hours Example 33 85°C.: 6 hours 60° C. 40%: 20.2 215 7 hours Example 34 85° C.: 6 hours 40°C. 70% 27.9 190 RH: 14 hours Example 35 85° C.: 6 hours 60° C. 40% 8.7154 RH: 3 hours Example 36 85° C.: 6 hours 60° C. 40% 14.5 152 RH: 5hours Example 37 85° C.: 6 hours 40° C. 70% 8.0 153 RH: 4 hours Example38 85° C.: 6 hours 85° C. 85% 332.3 168 RH: 20 hours

TABLE 4 Material used and amount [g] thereof Solution H (compositioncontaining Solution D copper alkyl-based phosphonate Thick- (compositioncontaining copper phenyl-based phosphonate) Alkyl- ness Phenyl-basedbased [μm] phosphonic acid phosphonic of Phenyl- 4-bromo- Copper acidCopper UV- phos- phenyl- Phosphoric Alkoxysilane acetate n-butyl-Phosphoric acetate Matrix IR- phonic phosphonic acid ester monomer mono-phosphonic acid ester mono- (silicone absorb- acid acid A208N A208F MTESTEOS hydrate acid A208N A208F hydrate resin) ing [g] [g] [g] [g] [g] [g][g] [g] [g] [g] [g] [g] layer Comparative 0.441 0.661 0.412 0     2.1660.710 1.125 0     0     0     0     2.200 126 Example 1 Comparative0.582 0.374 0.624 0     2.321 0.761 1.125 0     0     0     0     4.400217 Example 2 Comparative 0.832 0     0     0.624 1.274 1.012 1.1250     0     0     0     4.400 198 Example 3 Comparative 0     0    0     0     0     0     0     0.670 0     0.891 1.125 4.400 1002 Example4 Comparative 0.176 1.058 0.412 0     2.166 0.710 1.125 0.289 0.2570     0.450 2.200 191 Example 5 Comparative 0.176 1.058 0.412 0    2.166 0.710 1.125 0.289 0.257 0     0.450 2.200 217 Example 6Comparative 0.176 1.058 0.412 0     2.166 0.710 1.125 0.289 0.257 0    0.450 2.200 218 Example 7 Comparative 0.441 0.661 0.412 0     2.1660.710 1.125 0.134 0     0.178 0.225 2.200 — Example 8 Comparative 0    0     0     0     0     0     0     0.722 0.643 0     1.125 2.200 —Example 9

TABLE 5 Amount- Amount- Solution H of- of-sub- (composition substancestance containing ratio of ratio of Solution D (composition containingcopper alkyl-based halo- phenyl- Content ratio copper phenyl-basedphosphonate) phosphonate) genated based (mol) between Phenyl-basedAlkyl- phenyl- phos- phosphonic acids phosphonic acid based phos- phonicin total 4-bromo- phosphonic phonic acid to phosphonic acids Phenyl-phenyl- Copper acid Copper acid to alkyl- 4-bromo- n- phos- phos-Alkoxysilane acetate n-butyl- acetate phenyl- based phenyl- Phenyl-butyl- phonic phonic monomer mono- phosphonic mono- phos- phos- phos-phos- phos- acid acid MTES TEOS hydrate acid hydrate phonic phonicphonic phonic phonic [mol] [mol] [mol] [mol] [mol] [mol] [mol] acid acidacid acid acid Comparative 0.00279 0.00279 0.0121 0.00341 0.00563 0     0      1.0 — 50.0 50.0 0.0 Example 1 Comparative 0.00368 0.00158 0.01300.00365 0.00563 0      0      0.4 — 70.0 30.0 0.0 Example 2 Comparative0.00526 0       0.00715 0.00486 0.00563 0      0      0.0 — 100.0 0.00.0 Example 3 Comparative 0      0      0     0      0      0.004850.00563 — 0.0 0.0 0.0 100.0 Example 4 Comparative 0.00112 0.00446 0.01210.00341 0.00563 0.00209 0.00225 4.0 2.7 14.6 58.1 27.2 Example 5Comparative 0.00112 0.00446 0.0121 0.00341 0.00563 0.00209 0.00225 4.02.7 14.6 58.1 27.2 Example 6 Comparative 0.00112 0.00446 0.0121 0.003410.00563 0.00209 0.00225 4.0 2.7 14.6 58.1 27.2 Example 7 Comparative0.00279 0.00279 0.0121 0.00341 0.00563  0.000970 0.00113 1.0 5.8 42.642.6 14.8 Example 8 Comparative 0      0      0      0      0     0.00522 0.00563 0.0 0.0 0.0 100.0 Example 9

TABLE 6 Water vapor Conditions of Conditions of exposure heat treatmenthumidification amount for curing film treatment [mol/m³ · hour]Comparative  85° C.: 6 hours 85° C. 85% RH: 332.3 Example 1 20 hoursComparative  85° C.: 3 hours, 85° C. 85% RH: 66.5 Example 2 125° C.: 3hours, 4 hours 150° C.: 1 hour, 170° C.: 3 hours Comparative  85° C.: 3hours, 85° C. 85% RH: 332.3 Example 3 125° C.: 3 hours, 20 hours 150°C.: 1 hour, 170° C.: 3 hours Comparative  85° C.: 3 hours, — — Example4125° C.: 3 hours, 150° C.: 1 hour, 170° C.: 3 hours Comparative  85° C.:6 hours — — Example5 Comparative  85° C.: 6 hours 60° C. 40% RH: 2.9Example6 1 hour Comparative  85° C.: 6 hours 40° C. 70% RH: 2.0 Example71 hour

TABLE 7 Visible region properties Infrared region properties Ultravioletregion (i) (ii) (vi) (vii) properties Average Maximum Maximum Maximum(iii) (iii) Cut-off wavelength Thick- trans- trans- trans- trans-Maximum Maximum properties ness mittance mittance mittance mittancetransmittance transmittance (iv) (v) [μm] of [%] in [%] in [%] in [%] in[%] in [%] in IR UV UV- wavelength wavelength wavelength wavelengthwavelength wavelength cut-off cut-off IR- Require- range of range ofrange of range of range of range of wave- wave- ab- ment 450 to 750 to1000 to 1100 to 300 to 350 300 to 360 length length sorbing Example 600nm 1080 nm 1100 nm 1200 nm nm nm [nm] [nm] layer Ex. 1 85.48 0.99 1.6012.11  0.00 0.02 629 391 170 Ex. 2 85.67 0.44 0.72 5.82 0.03 0.03 639407 135 Ex. 3 80.82 0.05 0.01 0.50 0.00 0.00 634 413 178 Ex. 4 82.830.08 0.13 2.41 0.00 0.00 634 412 154 Ex. 5 83.41 0.72 1.21 10.61  0.000.00 633 412 143 Ex. 6 81.68 0.05 0.01 0.44 0.00 0.00 634 413 212 Ex. 782.92 0.08 0.13 2.28 0.00 0.00 633 411 182 Ex. 8 82.46 0.77 1.29 11.04 0.00 0.00 633 413 162 Ex. 9 81.00 0.05 0.01 0.38 0.00 0.00 634 407 193Ex. 10 82.52 0.09 0.15 2.40 0.00 0.00 633 406 152 Ex. 11 83.49 0.07 0.040.87 0.00 0.00 630 398 180 Ex. 12 83.00 0.08 0.12 1.94 0.00 0.00 630 399171 Ex. 13 83.01 0.22 0.37 4.42 0.00 0.00 629 398 158 Ex. 14 82.62 0.360.61 6.50 0.00 0.00 631 400 152 Ex. 15 84.14 0.81 1.36 11.52  0.00 0.00632 399 140 Ex. 16 83.99 0.43 0.71 5.70 0.03 0.03 638 408 132 Ex. 1784.75 0.06 0.08 1.96 0.00 0.00 632 408 193 Ex. 18 85.36 0.04 0.01 0.340.00 0.00 634 407 183 Ex. 19 82.40 0.07 0.04 0.96 0.00 0.00 632 409 198Ex. 20 83.23 0.07 0.04 1.03 0.00 0.01 630 393 168 Ex. 21 80.60 1.00 1.376.84 0.02 0.14 621 400 76 Ex. 22 85.22 0.10 0.17 2.64 0.00 0.00 632 406179 Ex. 23 85.61 0.09 0.15 2.50 0.00 0.00 633 406 177 Ex. 24 84.94 0.080.11 2.03 0.00 0.00 632 408 170 Ex. 25 84.51 0.16 0.26 3.27 0.00 0.00629 403 170 Ex. 26 85.83 0.17 0.27 3.27 0.00 0.00 630 404 175 Ex. 2785.79 0.13 0.22 2.96 0.00 0.00 631 404 174 Ex. 28 85.42 0.12 0.20 2.910.00 0.00 632 405 168 Ex. 29 84.19 0.21 0.33 3.62 0.00 0.00 627 403 175Ex. 30 84.78 0.19 0.30 3.34 0.00 0.00 627 404 178 Ex. 31 85.66 0.13 0.213.00 0.00 0.00 630 403 160 Ex. 32 85.98 0.12 0.20 2.84 0.00 0.00 631 403164 Ex. 33 84.11 0.11 0.07 1.10 0.00 0.00 620 406 215 Ex. 34 83.49 0.120.17 2.13 0.00 0.00 623 404 190 Ex. 35 84.53 0.94 0.72 4.46 0.00 0.01628 402 154 Ex. 36 85.36 0.95 0.78 4.80 0.00 0.01 632 402 152 Ex. 3783.77 0.91 0.69 4.25 0.00 0.02 625 400 153 Ex. 38 80.61 0.30 0.40 3.700.00 0.02 635 412 168

TABLE 8 Visible region properties Infrared region properties WavelengthMaximum Maximum Ultraviolet region properties range [nm] intransmittance transmittance Wavelength Wavelength Wavelength Wavelengthwhich [%] in [%] in range [nm] in range [nm] in range [nm] in range [nm]in transmittance wavelength wavelength which which which which is 78% orrange of 800 range of 800 transmittance transmittance transmittancetransmittance Example more to 950 nm to 1000 nm is 1% or less is 0.1% orless is 1% or less is 0.1% or less Example 1 408 to 599 0.08 0.18 713 to1080 753 to 965 300 to 368 300 to 363 Example 2 430 to 609 0.28 0.28 730to 1120 778 to 910 300 to 378 300 to 369 Example 3 456 to 602 0.00 0.00713 to 1200  743 to 1156 300 to 383 300 to 376 Example 4 440 to 603 0.000.01 713 to 1167  746 to 1089 300 to 383 300 to 376 Example 5 436 to 6020.04 0.11 713 to 1092 752 to 994 300 to 384 300 to 377 Example 6 443 to603 0.00 0.00 713 to 1200  743 to 1160 300 to 384 300 to 377 Example 7437 to 603 0.00 0.01 713 to 1170  747 to 1091 300 to 382 300 to 376Example 8 448 to 602 0.04 0.12 713 to 1090 752 to 990 300 to 384 300 to377 Example 9 443 to 602 0.00 0.00 713 to 1200  743 to 1165 300 to 379300 to 373 Example 10 435 to 602 0.01 0.02 713 to 1167  747 to 1086 300to 379 300 to 373 Example 11 421 to 598 0.00 0.01 713 to 1200  746 to1133 300 to 373 300 to 367 Example 12 428 to 599 0.01 0.02 713 to 1176 747 to 1094 300 to 373 300 to 368 Example 13 423 to 597 0.02 0.05 713to 1138  750 to 1043 300 to 373 300 to 367 Example 14 429 to 600 0.020.06 713 to 1119  750 to 1023 300 to 374 300 to 369 Example 15 422 to602 0.04 0.13 713 to 1087 752 to 988 300 to 375 300 to 369 Example 16434 to 606 0.27 0.27 730 to 1120 778 to 910 300 to 378 300 to 370Example 17 431 to 602 0.00 0.00 711 to 1177  743 to 1103 300 to 380 300to 374 Example 18 427 to 604 0.02 0.02 712 to 1200  741 to 1172 300 to380 300 to 373 Example 19 433 to 601 0.00 0.01 713 to 1200  745 to 1130300 to 380 300 to 374 Example 20 419 to 599 0.00 0.00 713 to 1199  745to 1132 300 to 369 300 to 364 Example 21 423 to 575 0.19 0.34 742 to1080 805 to 906 300 to 368 300 to 358 Example 22 424 to 601 0.01 0.02713 to 1163  748 to 1079 300 to 379 300 to 373 Example 23 424 to 6030.01 0.02 713 to 1167  747 to 1085 300 to 380 300 to 374 Example 24 429to 602 0.00 0.01 713 to 1175  746 to 1097 300 to 381 300 to 375 Example25 421 to 598 0.01 0.03 713 to 1152  750 to 1059 300 to 377 300 to 371Example 26 420 to 600 0.01 0.04 713 to 1151  750 to 1056 300 to 378 300to 372 Example 27 421 to 601 0.01 0.03 713 to 1157  749 to 1067 300 to379 300 to 373 Example 28 423 to 602 0.01 0.02 713 to 1159  748 to 1072300 to 379 300 to 373 Example 29 422 to 595 0.02 0.05 713 to 1146  753to 1044 300 to 377 300 to 370 Example 30 422 to 595 0.02 0.04 713 to1149  753 to 1049 300 to 377 300 to 371 Example 31 420 to 600 0.01 0.02713 to 1157  750 to 1069 300 to 377 300 to 371 Example 32 420 to 6010.01 0.02 713 to 1160  749 to 1074 300 to 377 300 to 371 Example 33 425to 587 0.01 0.01 713 to 1196  753 to 1115 300 to 379 300 to 372 Example34 423 to 590 0.01 0.03 713 to 1170  754 to 1073 300 to 377 300 to 371Example 35 420 to 591 0.15 0.25 749 to 1121 806 to 922 300 to 373 300 to366 Example 36 420 to 595 0.15 0.26 749 to 1116 806 to 923 300 to 373300 to 366 Example 37 420 to 586 0.14 0.25 748 to 1123 807 to 923 300 to372 300 to 364 Example 38 465 to 591 0.25 0.25 725 to 1147 764 to 977300 to 380 300 to 372

TABLE 9 Visible region properties Infrared region properties Ultravioletregion (i) (ii) (vi) (vii) properties Average Maximum Maximum Maximum(iii) (iii) Cut-off transmittance transmittance transmittancetransmittance Maximum Maximum wavelength properties [%] in [%] in [%] in[%] in transmittance transmittance (iv) (v) Thickness wavelengthwavelength wavelength wavelength [%] in [%] in IR cut-off UV cut-off[μm] of range of range of range of range of wavelength wavelength wave-wave- UV-IR- Requirement 450 to 750 to 1000 to 1100 to range of range oflength length absorbing Example 600 nm 1080 nm 1100 nm 1200 nm 300 to350 300 to 360 [nm] [nm] layer Comparative 86.06 7.21 11.63 48.16 0.000.00 632 400 126 Example 1 Comparative 82.84 1.64 3.49 33.05 0.00 0.00619 407 200 Calculation Example 1 Comparative 86.13 7.02 11.20 46.570.00 0.00 632 395 217 Example 2 Comparative 82.83 1.50 3.16 30.93 0.000.00 619 402 347 Calculation Example 2 Comparative 84.68 7.61 12.1349.45 0.00 0.02 631 391 198 Example 3 Comparative 81.06 2.02 4.13 35.540.00 0.00 619 398 303 Calculation Example 3 Comparative 79.21 0.00 0.000.00 1.01 13.75 646 376 1002 Example 4 Comparative 76.75 0.00 0.00 0.000.38 9.15 641 380 1216 Calculation Example 4-A Comparative 82.03 1.000.00 0.00 16.24 44.31 676 362 385 Calculation Example 4-B Comparative76.14 0.27 0.21 1.68 0.00 0.00 600 409 191 Example 5 Comparative 79.291.00 0.82 4.14 0.00 0.04 601 404 148 Calculation Example 5 Comparative79.81 0.16 0.08 1.04 0.00 0.00 605 408 217 Example 6 Comparative 83.031.00 0.59 3.74 0.00 0.01 618 403 155 Calculation Example 6 Comparative77.34 0.20 0.10 1.08 0.00 0.00 600 407 218 Example 7 Comparative 80.781.00 0.58 3.44 0.00 0.04 609 402 161 Calculation Example 7

TABLE 10 Visible region properties Infrared region properties WavelengthMaximum Maximum Ultraviolet region properties range [nm] intransmittance transmittance Wavelength Wavelength Wavelength Wavelengthwhich [%] in [%] in range [nm] in range [nm] in range [nm] in range [nm]in transmittance wavelength wavelength which which which which is 78% orrange of 800 range of 800 transmittance transmittance transmittancetransmittance Example more to 950 nm to 1000 nm is 1% or less is 0.1% orless is 1% or less is 0.1% or less Comparative 424 to 603 0.36 1.06 713to 996 764 to 904  300 to 375 300 to 369 Example 1 Comparative 462 to593 0.01 0.08  686 to 1067 710 to 1006 300 to 380 300 to 375 CalculationExample 1 Comparative 417 to 603 0.36 1.07 713 to 996 761 to 907  300 to371 300 to 366 Example 2 Comparative 441 to 592 0.01 0.07  686 to 1069709 to 1008 300 to 376 300 to 372 Calculation Example 2 Comparative 421to 601 0.37 1.17 713 to 992 762 to 908  300 to 367 300 to 363 Example 3Comparative 450 to 590 0.02 0.11  688 to 1061 712 to 996  300 to 372 300to 367 Calculation Example 3 Comparative 486 to 613 0.00 0.00  712 to1200 727 to 1200 300 to 349 300 to 345 Example 4 Comparative 508 to 6060.00 0.00  705 to 1200 720 to 1200 300 to 352 300 to 347 CalculationExample 4-A Comparative 403 to 642 0.00 0.00  750 to 1200 772 to 1200300 to 339 300 to 334 Calculation Example 4-B Comparative 438 to 5570.04 0.08  714 to 1178 776 to 1024 300 to 375 300 to 368 Example 5Comparative 430 to 564 0.25 0.40  750 to 1116 839 to 850  300 to 371 300to 362 Calculation Example 5 Comparative 432 to 569 0.01 0.02  714 to1198 760 to 1111 300 to 378 300 to 371 Example 6 Comparative 423 to 5790.15 0.23  750 to 1133 811 to 937  300 to 373 300 to 365 CalculationExample 6 Comparative 435 to 561 0.02 0.03  714 to 1197 766 to 1101 300to 375 300 to 369 Example 7 Comparative 425 to 571 0.17 0.25  750 to1135 818 to 919  300 to 370 300 to 362 Calculation Example 7

TABLE 11 Visible region properties Infrared region propertiesUltraviolet region properties (i) (ii) (vi) (vii) (iii) (iii) AverageMaximum Maximum Maximum Maximum Maximum Cut-off transmittancetransmittance transmittance transmittance transmittance transmittancewavelength properties [%] in [%] in [%] in [%] in [%] in [%] in (iv) (v)Require- wavelength wavelength wavelength wavelength wavelengthwavelength IR cut-off UV cut-off ment range of range of range of rangeof range of range of wave- wave- Incident 450 to 750 to 1000 to 1100 to300 to 300 to length length angle [°] 600 nm 1080 nm 1100 nm 1200 nm 350nm 360 nm [nm] [nm]  0 85.48 0.99 1.60 12.11 0.00 0.02 629 391 30 83.990.88 1.44 11.36 0.00 0.02 627 392 35 83.35 0.83 1.37 11.04 0.00 0.01 626392 40 82.63 0.79 1.31 10.71 0.00 0.01 626 393 45 81.75 0.75 1.26 10.300.00 0.01 625 393 50 80.49 0.71 1.19 9.85 0.00 0.01 623 394 55 78.060.67 1.12 9.31 0.00 0.01 621 395 60 73.14 0.00 1.03 8.57 0.00 0.00 618398 65 65.87 0.56 0.93 7.67 0.00 0.00 612 402

TABLE 12 Visible region properties Wavelength Infrared region propertiesUltraviolet region properties range [nm] in Wavelength WavelengthWavelength Wavelength which range [nm] in range [nm] in range [nm] inrange [nm] in transmittance which which which which Incident is 78% ortransmittance transmittance transmittance transmittance angle [°] moreis 1% or less is 0.1% or less is 1% or less is 0.1% or less 0 413 to 594713 to 1080 753 to 965 300 to 368 300 to 363 30 418 to 590 710 to 1085748 to 970 300 to 369 300 to 363 35 420 to 589 709 to 1087 746 to 980300 to 369 300 to 364 40 421 to 586 707 to 1088 744 to 981 300 to 369300 to 364 45 425 to 584 706 to 1091 743 to 986 300 to 370 300 to 364 50439 to 580 705 to 1092 741 to 991 300 to 370 300 to 365 55 478 to 571703 to 1095 738 to 991 300 to 370 300 to 365 60 — 702 to 1099 736 to 996300 to 371 300 to 366 65 — 699 to 1102  733 to 1003 300 to 371 300 to366

TABLE 13 Visible region properties Infrared region propertiesUltraviolet region properties (i) (ii) (vi) (vii) (iii) (iii) AverageMaximum Maximum Maximum Maximum Maximum Cut-off transmittancetransmittance transmittance transmittance transmittance transmittancewavelength properties [%] in [%] in [%] in [%] in [%] in [%] in (iv) (v)Require- wavelength wavelength wavelength wavelength wavelengthwavelength IR cut-off UV cut-off ment range of range of range of rangeof range of range of wave- wave- Incident 450 to 750 to 1000 to 1100 to300 to 300 to length length angle [°] 600 nm 1080 nm 1100 nm 1200 nm 350nm 360 nm [nm] [nm]  0 85.67 0.44 0.72 5.82 0.03 0.03 639 407 30 83.300.38 0.62 5.24 0.02 0.02 637 409 35 82.72 0.37 0.61 5.17 0.02 0.02 636409 40 81.52 0.36 0.61 4.97 0.02 0.02 635 410 45 80.19 0.37 0.56 4.810.03 0.03 634 411 50 78.56 0.38 0.56 4.68 0.02 0.03 632 412 55 75.760.36 0.55 4.52 0.02 0.02 630 414 60 71.73 0.00 0.54 4.30 0.03 0.03 627416 65 66.20 0.35 0.55 4.05 0.03 0.03 621 420

TABLE 14 Visible region properties Wavelength Infrared region propertiesUltraviolet region properties range [nm] in Wavelength WavelengthWavelength Wavelength which range [nm] in range [nm] in range [nm] inrange [nm] in transmittance which which which which Incident is 78% ortransmittance transmittance transmittance transmittance angle [°] moreis 1% or less is 0.1% or less is 1% or less is 0.1% or less 0 438 to 603730 to 1120 778 to 910 300 to 378 300 to 369 30 456 to 598 726 to 1123771 to 974 300 to 379 300 to 372 35 462 to 596 725 to 1124 771 to 923300 to 379 300 to 372 40 467 to 593 724 to 1127 768 to 950 300 to 380300 to 373 45 472 to 589 723 to 1128 768 to 956 300 to 380 300 to 373 50482 to 582 721 to 1129  766 to 1004 300 to 381 300 to 373 55 527 to 560720 to 1130 765 to 971 300 to 381 300 to 374 60 — 718 to 1134 762 to 981300 to 382 300 to 375 65 — 716 to 1134 761 to 982 300 to 382 300 to 375

TABLE 15 Visible region properties Infrared region propertiesUltraviolet region properties (i) (ii) (vi) (vii) (iii) (iii) AverageMaximum Maximum Maximum Maximum Maximum Cut-off transmittancetransmittance transmittance transmittance transmittance transmittancewavelength properties [%] in [%] in [%] in [%] in [%] in [%] in (iv) (v)Require- wavelength wavelength wavelength wavelength wavelengthwavelength IR cut-off UV cut-off ment range of range of range of rangeof range of range of wave- wave- Incident 450 to 750 to 1000 to 1100 to300 to 300 to length length angle [°] 600 nm 1080 nm 1100 nm 1200 nm 350nm 360 nm [nm] [nm]  0 83.99 0.43 0.71 5.70 0.03 0.03 638 408 30 81.670.38 0.61 5.14 0.02 0.02 636 409 35 81.09 0.36 0.59 5.06 0.02 0.02 635410 40 79.92 0.35 0.60 4.88 0.02 0.02 634 411 45 78.62 0.37 0.55 4.710.03 0.03 633 412 50 77.02 0.37 0.55 4.59 0.02 0.03 631 413 55 74.280.35 0.54 4.43 0.02 0.02 629 414 60 70.32 0.00 0.53 4.21 0.03 0.03 625417 65 64.90 0.34 0.54 3.97 0.03 0.03 619 422

TABLE 16 Visible region properties Wavelength Infrared region propertiesUltraviolet region properties range [nm] in Wavelength WavelengthWavelength Wavelength which range [nm] in range [nm] in range [nm] inrange [nm] in transmittance which which which which Incident is 78% ortransmittance transmittance transmittance transmittance angle [°] moreis 1% or less is 0.1% or less is 1% or less is 0.1% or less 0 446 to 600730 to 1120 778 to 910 300 to 378 300 to 370 30 466 to 594 726 to 1124771 to 956 300 to 379 300 to 372 35 469 to 592 725 to 1125 769 to 976300 to 379 300 to 372 40 473 to 588 723 to 1127 768 to 943 300 to 380300 to 373 45 480 to 583 722 to 1128 767 to 961 300 to 380 300 to 373 50499 to 573 721 to 1130  765 to 1009 300 to 381 300 to 373 55 — 719 to1132 765 to 854 300 to 381 300 to 374 60 — 718 to 1135 761 to 852 300 to382 300 to 375 65 — 716 to 1132 761 to 982 300 to 382 300 to 375

TABLE 17 Visible region properties Infrared region propertiesUltraviolet region properties (i) (ii) (vi) (vii) (iii) (iii) AverageMaximum Maximum Maximum Maximum Maximum Cut-off transmittancetransmittance transmittance transmittance transmittance transmittancewavelength properties [%] in [%] in [%] in [%] in [%] in [%] in (iv) (v)Require- wavelength wavelength wavelength wavelength wavelengthwavelength IR cut-off UV cut-off ment range of range of range of rangeof range of range of wave- wave- Incident 450 to 750 to 1000 to 1100 to300 to 300 to length length angle [°] 600 nm 1080 nm 1100 nm 1200 nm 350nm 360 nm [nm] [nm]  0 84.75 0.06 0.08 1.96 0.00 0.00 632 408 30 83.730.04 0.07 1.69 0.00 0.00 630 410 35 83.25 0.04 0.05 1.62 0.00 0.00 630410 40 82.55 0.03 0.05 1.55 0.00 0.00 629 411 45 81.04 0.03 0.05 1.460.00 0.00 628 412 50 79.25 0.03 0.05 1.37 0.00 0.00 626 413 55 77.060.03 0.04 1.26 0.00 0.00 624 414 60 73.44 0.00 0.03 1.17 0.00 0.00 620417 65 67.66 0.02 0.03 1.04 0.00 0.00 616 420

TABLE 18 Visible region properties Wavelength Infrared region propertiesUltraviolet region properties range [nm] in Wavelength WavelengthWavelength Wavelength which range [nm] in range [nm] in range [nm] inrange [nm] in transmittance which which which which Incident is 78% ortransmittance transmittance transmittance transmittance angle [°] moreis 1% or less is 0.1% or less is 1% or less is 0.1% or less 0 439 to 596711 to 1177 778 to 910  300 to 380 300 to 374 30 444 to 594 708 to 1182739 to 1109 300 to 382 300 to 375 35 447 to 593 708 to 1183 738 to 1110300 to 382 300 to 376 40 454 to 591 706 to 1185 737 to 1113 300 to 382300 to 376 45 466 to 588 705 to 1187 734 to 1118 300 to 383 300 to 37750 474 to 582 704 to 1189 733 to 1120 300 to 383 300 to 377 55 493 to569 702 to 1191 731 to 1121 300 to 384 300 to 378 60 — 700 to 1194 728to 1121 300 to 385 300 to 378 65 — 698 to 1199 726 to 1130 300 to 385300 to 379

TABLE 19 Visible region properties Infrared region propertiesUltraviolet region properties (i) (ii) (vi) (vii) (iii) (iii) AverageMaximum Maximum Maximum Maximum Maximum Cut-off transmittancetransmittance transmittance transmittance transmittance transmittancewavelength properties [%] in [%] in [%] in [%] in [%] in [%] in (iv) (v)Require- wavelength wavelength wavelength wavelength wavelengthwavelength IR cut-off UV cut-off ment range of range of range of rangeof range of range of wave- wave- Incident 450 to 750 to 1000 to 1100 to300 to 300 to length length angle [°] 600 nm 1080 nm 1100 nm 1200 nm 350nm 360 nm [nm] [nm]  0 85.36 0.04 0.01 0.34 0.00 0.00 634 407 30 83.910.03 0.02 0.28 0.00 0.00 631 409 35 83.28 0.03 0.01 0.27 0.00 0.00 631409 40 82.56 0.03 0.01 0.25 0.00 0.00 630 410 45 81.51 0.03 0.01 0.240.00 0.00 629 411 50 79.71 0.03 0.01 0.21 0.00 0.00 627 411 55 77.530.03 0.01 0.21 0.00 0.00 625 412 60 74.21 0.00 0.01 0.19 0.00 0.00 621415 65 69.45 0.01 0.01 0.16 0.00 0.00 616 419

TABLE 20 Visible region properties Wavelength Infrared region propertiesUltraviolet region properties range [nm] in Wavelength WavelengthWavelength Wavelength which range [nm] in range [nm] in range [nm] inrange [nm] in transmittance which which which which Incident is 78% ortransmittance transmittance transmittance transmittance angle [°] moreis 1% or less is 0.1% or less is 1% or less is 0.1% or less 0 434 to 598712 to 1200 778 to 910  300 to 380 300 to 373 30 440 to 595 709 to 1200737 to 1174 300 to 381 300 to 375 35 443 to 593 708 to 1200 736 to 1175300 to 381 300 to 375 40 447 to 591 707 to 1200 735 to 1176 300 to 382300 to 375 45 458 to 589 706 to 1200 733 to 1179 300 to 382 300 to 37650 472 to 584 705 to 1200 732 to 1179 300 to 382 300 to 376 55 488 to572 703 to 1200 730 to 1182 300 to 383 300 to 377 60 — 701 to 1200 728to 1184 300 to 384 300 to 378 65 — 699 to 1200 726 to 1186 300 to 384300 to 378

The invention claimed is:
 1. An optical filter comprising: aUV-IR-absorbing layer comprising a UV-IR absorber that comprises aphosphonic acid and copper ion, wherein when light with wavelengths of300 nm to 1200 nm is incident on the optical filter at an incident angleof 0°, (i) the optical filter has an average transmittance of 78% ormore in the wavelength range of 450 nm to 600 nm, (ii) the opticalfilter has a maximum transmittance of 1% or less in the wavelength rangeof 750 nm to 1080 nm, (iii) the optical filter has a maximumtransmittance of 1% or less in the wavelength range of 300 nm to 350 nm,(iv) the optical filter has a decreasing spectral transmittance withincreasing wavelength in the wavelength range of 600 nm to 750 nm and afirst IR cut-off wavelength at which the spectral transmittance is 50%is in the wavelength range of 620 nm to 680 nm, and (v) the opticalfilter has an increasing spectral transmittance with increasingwavelength in the wavelength range of 350 nm to 450 nm and a first UVcut-off wavelength at which the spectral transmittance is 50% is in thewavelength range of 380 nm to 430 nm.
 2. The optical filter according toclaim 1, wherein when light with wavelengths of 300 nm to 1200 nm isincident on the optical filter at an incident angle of 0°, (vi) theoptical filter has a maximum transmittance of 3% or less in thewavelength range of 1000 nm to 1100 nm.
 3. The optical filter accordingto claim 1, wherein when light with wavelengths of 300 nm to 1200 nm isincident on the optical filter at an incident angle of 0°, (vii) theoptical filter has a maximum transmittance of 15% or less in thewavelength range of 1100 nm to 1200 nm.
 4. The optical filter accordingto claim 1, wherein when light with wavelengths of 300 nm to 1200 nm isincident on the optical filter at an incident angle of 40°, the opticalfilter has a second IR cut-off wavelength at which the spectraltransmittance is 50% in the wavelength range of 600 nm to 750 nm, andwherein an absolute value of a difference between the first IR cut-offwavelength and the second IR cut-off wavelength is 10 nm or less.
 5. Theoptical filter according to claim 1, wherein when light with wavelengthsof 300 nm to 1200 nm is incident on the optical filter at an incidentangle of 50°, the optical filter has a third IR cut-off wavelength atwhich the spectral transmittance is 50% in the wavelength range of 600nm to 750 nm, and wherein an absolute value of a difference between thefirst IR cut-off wavelength and the third IR cut-off wavelength is 15 nmor less.
 6. The optical filter according to claim 1, wherein when lightwith wavelengths of 300 nm to 1200 nm is incident on the optical filterat an incident angle of 40°, the optical filter has a second UV cut-offwavelength at which the spectral transmittance is 50% in the wavelengthrange of 350 nm to 450 nm, and wherein an absolute value of a differencebetween the first UV cut-off wavelength and the second UV cut-offwavelength is 10 nm or less.
 7. The optical filter according to claim 1,wherein when light with wavelengths of 300 nm to 1200 nm is incident onthe optical filter at an incident angle of 50°, the optical filter has athird UV cut-off wavelength at which the spectral transmittance is 50%in the wavelength range of 340 nm to 450 nm, and wherein an absolutevalue of a difference between the first UV cut-off wavelength and thethird UV cut-off wavelength is 15 nm or less.
 8. The optical filteraccording to claim 1, wherein the phosphonic acid comprises a firstphosphonic acid having an aryl group.
 9. The optical filter according toclaim 8, wherein the first phosphonic acid comprises a portion that hasa halogenated phenyl group in which at least one hydrogen atom of aphenyl group is substituted by a halogen atom.
 10. The optical filteraccording to claim 8, wherein the phosphonic acid further comprises asecond phosphonic acid having an alkyl group.
 11. The optical filteraccording to claim 1, wherein the UV-IR-absorbing layer is formed as asingle layer.